Merge pull request #4377 from jacktose/force-brewed-git

Implement HOMEBREW_FORCE_BREWED_GIT

Library/Homebrew/brew.sh

@@ -102,6 +102,7 @@ then
   if [[ "$HOMEBREW_MACOS_VERSION_NUMERIC" -lt "100900" ]]
   then
     HOMEBREW_SYSTEM_GIT_TOO_OLD="1"
+    HOMEBREW_FORCE_BREWED_GIT="1"
   fi
 
   if [[ -z "$HOMEBREW_CACHE" ]]
@@ -135,6 +136,15 @@ else
   HOMEBREW_CURL="curl"
 fi
 
+if [[ -n "$HOMEBREW_FORCE_BREWED_GIT" &&
+      -x "$HOMEBREW_PREFIX/opt/git/bin/git" ]] &&
+         "$HOMEBREW_PREFIX/opt/git/bin/git" --version >/dev/null
+then
+  HOMEBREW_GIT="$HOMEBREW_PREFIX/opt/git/bin/git"
+else
+  HOMEBREW_GIT="git"
+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"

Library/Homebrew/cmd/update.sh

@@ -384,8 +384,8 @@ EOS
   fi
 
   if ! git --version &>/dev/null ||
-       [[ -n "$HOMEBREW_SYSTEM_GIT_TOO_OLD" &&
-        ! -x "$HOMEBREW_PREFIX/opt/git/bin/git" ]]
+     [[ -n "$HOMEBREW_FORCE_BREWED_GIT" &&
+      ! -x "$HOMEBREW_PREFIX/opt/git/bin/git" ]]
   then
     # we cannot install brewed git if homebrew/core is unavailable.
     [[ -d "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] && brew install git

Library/Homebrew/manpages/brew.1.md.erb

@@ -184,6 +184,10 @@ Note that environment variables must have a value set to be detected. For exampl
 
     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.
+
   * `HOMEBREW_GITHUB_API_TOKEN`:
     A personal access token for the GitHub API, which you can create at
     <https://github.com/settings/tokens>. If set, GitHub will allow you a

docs/Manpage.md

@@ -1167,6 +1167,10 @@ Note that environment variables must have a value set to be detected. For exampl
 
     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.
+
   * `HOMEBREW_GITHUB_API_TOKEN`:
     A personal access token for the GitHub API, which you can create at
     <https://github.com/settings/tokens>. If set, GitHub will allow you a

manpages/brew.1

@@ -1187,6 +1187,10 @@ When using Git, Homebrew will use \fBGIT\fR if set, a Homebrew\-built Git if ins
 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\.
+.
+.TP
 \fBHOMEBREW_GITHUB_API_TOKEN\fR
 A personal access token for the GitHub API, which you can create at \fIhttps://github\.com/settings/tokens\fR\. If set, GitHub will allow you a greater number of API requests\. See \fIhttps://developer\.github\.com/v3/#rate\-limiting\fR for more information\. Homebrew uses the GitHub API for features such as \fBbrew search\fR\.
 .