From baf75af908e7eff2c02d4e673e90bf0d1ec281d3 Mon Sep 17 00:00:00 2001
From: EricFromCanada <enk3@outlook.com>
Date: Wed, 24 Oct 2018 18:20:17 -0400
Subject: [PATCH 1/5] brew: prepend shims to PATH used by _system

Ensures `system` and `safe_system` use brewed git if available.
---
 Library/Homebrew/brew.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index ba8e445c8d..fcc78728d7 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -37,8 +37,8 @@ begin
   homebrew_path = PATH.new(ENV["HOMEBREW_PATH"])
 
   # Add SCM wrappers.
-  path.append(HOMEBREW_SHIMS_PATH/"scm")
-  homebrew_path.append(HOMEBREW_SHIMS_PATH/"scm")
+  path.prepend(HOMEBREW_SHIMS_PATH/"scm")
+  homebrew_path.prepend(HOMEBREW_SHIMS_PATH/"scm")
 
   ENV["PATH"] = path
 

From 9e4fb40f92ed2acadc82909cc3bc4b2d66467c2d Mon Sep 17 00:00:00 2001
From: EricFromCanada <enk3@outlook.com>
Date: Thu, 25 Oct 2018 09:24:00 -0400
Subject: [PATCH 2/5] docs: update descriptions of git- and curl-related vars

Note that the `HOMEBREW_FORCE_BREWED_` vars are automatically set if the system `git` and `curl` are too old. Drop mention of `HOMEBREW_GIT` which isn't user-settable.
---
 Library/Homebrew/manpages/brew.1.md.erb | 17 ++++++-----------
 Library/Homebrew/shims/scm/git          |  2 +-
 docs/Manpage.md                         | 17 ++++++-----------
 manpages/brew.1                         | 11 ++---------
 4 files changed, 15 insertions(+), 32 deletions(-)

diff --git a/Library/Homebrew/manpages/brew.1.md.erb b/Library/Homebrew/manpages/brew.1.md.erb
index b17b10a47a..3488c08878 100644
--- a/Library/Homebrew/manpages/brew.1.md.erb
+++ b/Library/Homebrew/manpages/brew.1.md.erb
@@ -10,7 +10,7 @@
 # When done, regenerate the man page and its HTML version by running `brew man`.
 %>
 brew(1) -- The missing package manager for macOS
-===============================================
+================================================
 
 ## SYNOPSIS
 
@@ -105,6 +105,7 @@ can take several different forms:
     The formula file will be cached for later use.
 
 ## ENVIRONMENT
+
 Note that environment variables must have a value set to be detected. For example, `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just `export HOMEBREW_NO_INSECURE_REDIRECT`.
 
   * `HOMEBREW_ARTIFACT_DOMAIN`:
@@ -180,22 +181,16 @@ Note that environment variables must have a value set to be detected. For exampl
     editors will do strange things in this case.
 
   * `HOMEBREW_FORCE_BREWED_CURL`:
-    If set, Homebrew will use a Homebrew-installed `curl` rather than the
-    system version.
+    If set, Homebrew will always use a Homebrew-installed `curl` rather than the
+    system version. Automatically set if the system version of `curl` is too old.
 
   * `HOMEBREW_FORCE_VENDOR_RUBY`:
     If set, Homebrew will always use its vendored, relocatable Ruby version
     even if the system version of Ruby is new enough.
 
-  * `HOMEBREW_GIT`:
-    When using Git, Homebrew will use `GIT` if set,
-    a Homebrew-built Git if installed, or the system-provided binary.
-
-    Set this to force Homebrew to use a particular git binary.
-
   * `HOMEBREW_FORCE_BREWED_GIT`:
-    If set, Homebrew will use a Homebrew-installed `git` rather than the
-    system version.
+    If set, Homebrew will always use a Homebrew-installed `git` rather than the
+    system version. Automatically set if the system version of `git` is too old.
 
   * `HOMEBREW_GITHUB_API_TOKEN`:
     A personal access token for the GitHub API, which you can create at
diff --git a/Library/Homebrew/shims/scm/git b/Library/Homebrew/shims/scm/git
index 0930c0adc3..c4e7ec5134 100755
--- a/Library/Homebrew/shims/scm/git
+++ b/Library/Homebrew/shims/scm/git
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-# This script because we support $GIT, $HOMEBREW_SVN, etc., Xcode-only and
+# This script because we support $HOMEBREW_GIT, $HOMEBREW_SVN, etc., Xcode-only and
 # no Xcode/CLT configurations. Order is careful to be what the user would want.
 
 set +o posix
diff --git a/docs/Manpage.md b/docs/Manpage.md
index 0dad55baa5..b7c0754964 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -1,5 +1,5 @@
 brew(1) -- The missing package manager for macOS
-===============================================
+================================================
 
 ## SYNOPSIS
 
@@ -1100,6 +1100,7 @@ can take several different forms:
     The formula file will be cached for later use.
 
 ## ENVIRONMENT
+
 Note that environment variables must have a value set to be detected. For example, `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just `export HOMEBREW_NO_INSECURE_REDIRECT`.
 
   * `HOMEBREW_ARTIFACT_DOMAIN`:
@@ -1175,22 +1176,16 @@ Note that environment variables must have a value set to be detected. For exampl
     editors will do strange things in this case.
 
   * `HOMEBREW_FORCE_BREWED_CURL`:
-    If set, Homebrew will use a Homebrew-installed `curl` rather than the
-    system version.
+    If set, Homebrew will always use a Homebrew-installed `curl` rather than the
+    system version. Automatically set if the system version of `curl` is too old.
 
   * `HOMEBREW_FORCE_VENDOR_RUBY`:
     If set, Homebrew will always use its vendored, relocatable Ruby version
     even if the system version of Ruby is new enough.
 
-  * `HOMEBREW_GIT`:
-    When using Git, Homebrew will use `GIT` if set,
-    a Homebrew-built Git if installed, or the system-provided binary.
-
-    Set this to force Homebrew to use a particular git binary.
-
   * `HOMEBREW_FORCE_BREWED_GIT`:
-    If set, Homebrew will use a Homebrew-installed `git` rather than the
-    system version.
+    If set, Homebrew will always use a Homebrew-installed `git` rather than the
+    system version. Automatically set if the system version of `git` is too old.
 
   * `HOMEBREW_GITHUB_API_TOKEN`:
     A personal access token for the GitHub API, which you can create at
diff --git a/manpages/brew.1 b/manpages/brew.1
index 4480c25ecd..95cccd299a 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1297,22 +1297,15 @@ If set, Homebrew will use this editor when editing a single formula, or several
 .
 .TP
 \fBHOMEBREW_FORCE_BREWED_CURL\fR
-If set, Homebrew will use a Homebrew\-installed \fBcurl\fR rather than the system version\.
+If set, Homebrew will always use a Homebrew\-installed \fBcurl\fR rather than the system version\. Automatically set if the system version of \fBcurl\fR is too old\.
 .
 .TP
 \fBHOMEBREW_FORCE_VENDOR_RUBY\fR
 If set, Homebrew will always use its vendored, relocatable Ruby version even if the system version of Ruby is new enough\.
 .
 .TP
-\fBHOMEBREW_GIT\fR
-When using Git, Homebrew will use \fBGIT\fR if set, a Homebrew\-built Git if installed, or the system\-provided binary\.
-.
-.IP
-Set this to force Homebrew to use a particular git binary\.
-.
-.TP
 \fBHOMEBREW_FORCE_BREWED_GIT\fR
-If set, Homebrew will use a Homebrew\-installed \fBgit\fR rather than the system version\.
+If set, Homebrew will always use a Homebrew\-installed \fBgit\fR rather than the system version\. Automatically set if the system version of \fBgit\fR is too old\.
 .
 .TP
 \fBHOMEBREW_GITHUB_API_TOKEN\fR

From 7c9bea27037d31cb903bdcd1acb0e58b31d7fa2f Mon Sep 17 00:00:00 2001
From: EricFromCanada <enk3@outlook.com>
Date: Thu, 25 Oct 2018 01:17:22 -0400
Subject: [PATCH 3/5] system_config: skip HOMEBREW_GIT as its final path is
 shown further down

---
 Library/Homebrew/system_config.rb | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/Library/Homebrew/system_config.rb b/Library/Homebrew/system_config.rb
index 23cdbffcef..e6a387cdbd 100644
--- a/Library/Homebrew/system_config.rb
+++ b/Library/Homebrew/system_config.rb
@@ -123,7 +123,6 @@ class SystemConfig
         HOMEBREW_CACHE: "#{ENV["HOME"]}/Library/Caches/Homebrew",
         HOMEBREW_TEMP: ENV["HOMEBREW_SYSTEM_TEMP"],
         HOMEBREW_RUBY_WARNINGS: "-W0",
-        HOMEBREW_GIT: "git",
       }.freeze
       boring_keys = %w[
         HOMEBREW_BROWSER
@@ -137,6 +136,7 @@ class SystemConfig
         HOMEBREW_BREW_FILE
         HOMEBREW_COMMAND_DEPTH
         HOMEBREW_CURL
+        HOMEBREW_GIT
         HOMEBREW_GIT_CONFIG_FILE
         HOMEBREW_LIBRARY
         HOMEBREW_MACOS_VERSION
@@ -168,9 +168,6 @@ class SystemConfig
       if defaults_hash[:HOMEBREW_RUBY_WARNINGS] != ENV["HOMEBREW_RUBY_WARNINGS"].to_s
         f.puts "HOMEBREW_RUBY_WARNINGS: #{ENV["HOMEBREW_RUBY_WARNINGS"]}"
       end
-      if defaults_hash[:HOMEBREW_GIT] != ENV["HOMEBREW_GIT"].to_s
-        f.puts "HOMEBREW_GIT: #{ENV["HOMEBREW_GIT"]}"
-      end
       unless ENV["HOMEBREW_ENV"]
         ENV.sort.each do |key, value|
           next unless key.start_with?("HOMEBREW_")

From 7aa995693479992a76e19a15132843d6fdf765f5 Mon Sep 17 00:00:00 2001
From: EricFromCanada <enk3@outlook.com>
Date: Fri, 26 Oct 2018 17:08:59 -0400
Subject: [PATCH 4/5] brew: check system-provided curl and git on Linux

Set HOMEBREW_FORCE_BREWED_CURL or HOMEBREW_FORCE_BREWED_GIT if the system-provided versions are missing or outdated, causing either to be installed on the next `brew update`.
---
 Library/Homebrew/brew.sh | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 135c77ded8..2f729b733e 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -55,6 +55,12 @@ git() {
   "$HOMEBREW_LIBRARY/Homebrew/shims/scm/git" "$@"
 }
 
+numeric() {
+  # Condense the exploded argument into a single return value.
+  # shellcheck disable=SC2086,SC2183
+  printf "%01d%02d%02d%02d" ${1//./ }
+}
+
 HOMEBREW_VERSION="$(git -C "$HOMEBREW_REPOSITORY" describe --tags --dirty --abbrev=7 2>/dev/null)"
 HOMEBREW_USER_AGENT_VERSION="$HOMEBREW_VERSION"
 if [[ -z "$HOMEBREW_VERSION" ]]
@@ -114,6 +120,25 @@ else
   : "${HOMEBREW_OS_VERSION:=$(uname -r)}"
   HOMEBREW_OS_USER_AGENT_VERSION="$HOMEBREW_OS_VERSION"
 
+  # Ensure the system Curl is a version that supports modern HTTPS certificates.
+  HOMEBREW_MINIMUM_CURL_VERSION="7.41.0"
+  system_curl_version_output="$($(command -v curl) --version 2>/dev/null)"
+  system_curl_name_and_version="${system_curl_version_output%% (*}"
+  if [[ $(numeric "${system_curl_name_and_version##* }") -lt $(numeric "$HOMEBREW_MINIMUM_CURL_VERSION") ]]
+  then
+    HOMEBREW_SYSTEM_CURL_TOO_OLD="1"
+    HOMEBREW_FORCE_BREWED_CURL="1"
+  fi
+
+  # Ensure the system Git is at or newer than the minimum required version.
+  # Git 2.7.4 is the version of git on Ubuntu 16.04 LTS (Xenial Xerus).
+  HOMEBREW_MINIMUM_GIT_VERSION="2.7.0"
+  system_git_version_output="$($(command -v git) --version 2>/dev/null)"
+  if [[ $(numeric "${system_git_version_output##* }") -lt $(numeric "$HOMEBREW_MINIMUM_GIT_VERSION") ]]
+  then
+    HOMEBREW_FORCE_BREWED_GIT="1"
+  fi
+
   CACHE_HOME="${XDG_CACHE_HOME:-${HOME}/.cache}"
   HOMEBREW_CACHE="${HOMEBREW_CACHE:-${CACHE_HOME}/Homebrew}"
   HOMEBREW_SYSTEM_TEMP="/tmp"
@@ -153,8 +178,9 @@ else
 fi
 
 HOMEBREW_USER_AGENT="$HOMEBREW_PRODUCT/$HOMEBREW_USER_AGENT_VERSION ($HOMEBREW_SYSTEM; $HOMEBREW_PROCESSOR $HOMEBREW_OS_USER_AGENT_VERSION)"
-HOMEBREW_CURL_VERSION="$("$HOMEBREW_CURL" --version 2>/dev/null | head -n1 | awk '{print $1"/"$2}')"
-HOMEBREW_USER_AGENT_CURL="$HOMEBREW_USER_AGENT $HOMEBREW_CURL_VERSION"
+curl_version_output="$("$HOMEBREW_CURL" --version 2>/dev/null)"
+curl_name_and_version="${curl_version_output%% (*}"
+HOMEBREW_USER_AGENT_CURL="$HOMEBREW_USER_AGENT ${curl_name_and_version// //}"
 
 # Declared in bin/brew
 export HOMEBREW_BREW_FILE

From 0362e66a2620cf18eeff68b3f53e84051fdadebf Mon Sep 17 00:00:00 2001
From: EricFromCanada <enk3@outlook.com>
Date: Sat, 27 Oct 2018 20:44:13 -0400
Subject: [PATCH 5/5] doctor: use minimum Git version set in brew.sh

---
 Library/Homebrew/brew.sh          | 4 +++-
 Library/Homebrew/diagnostic.rb    | 3 +--
 Library/Homebrew/system_config.rb | 1 +
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 2f729b733e..003e19a32d 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -105,7 +105,8 @@ then
     HOMEBREW_FORCE_BREWED_CURL="1"
   fi
 
-  # The system Git is too old for some Homebrew functionality we rely on.
+  # The system Git on macOS versions before Sierra is too old for some Homebrew functionality we rely on.
+  HOMEBREW_MINIMUM_GIT_VERSION="2.14.3"
   if [[ "$HOMEBREW_MACOS_VERSION_NUMERIC" -lt "101200" ]]
   then
     HOMEBREW_FORCE_BREWED_GIT="1"
@@ -198,6 +199,7 @@ export HOMEBREW_SYSTEM
 export HOMEBREW_CURL
 export HOMEBREW_SYSTEM_CURL_TOO_OLD
 export HOMEBREW_GIT
+export HOMEBREW_MINIMUM_GIT_VERSION
 export HOMEBREW_PROCESSOR
 export HOMEBREW_PRODUCT
 export HOMEBREW_OS_VERSION
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 7f84168060..55df9aca8c 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -489,8 +489,7 @@ module Homebrew
       end
 
       def check_git_version
-        # System Git version on macOS Sierra.
-        minimum_version = "2.14.3".freeze
+        minimum_version = ENV["HOMEBREW_MINIMUM_GIT_VERSION"].freeze
         return unless Utils.git_available?
         return if Version.create(Utils.git_version) >= Version.create(minimum_version)
 
diff --git a/Library/Homebrew/system_config.rb b/Library/Homebrew/system_config.rb
index e6a387cdbd..f5ed7bd37c 100644
--- a/Library/Homebrew/system_config.rb
+++ b/Library/Homebrew/system_config.rb
@@ -141,6 +141,7 @@ class SystemConfig
         HOMEBREW_LIBRARY
         HOMEBREW_MACOS_VERSION
         HOMEBREW_MACOS_VERSION_NUMERIC
+        HOMEBREW_MINIMUM_GIT_VERSION
         HOMEBREW_RUBY_PATH
         HOMEBREW_SYSTEM
         HOMEBREW_SYSTEM_TEMP