From 8aa18510c492c0167978df4e209455af4ff215e3 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Sat, 17 Sep 2016 13:25:32 +0100
Subject: [PATCH] Always run LinkedKegs migration (if needed).

Ensure that `brew update` always runs the LinkedKegs migration if needed
as it may not have been run by `brew update` if it was using `--preinstall` or
a `git pull` etc.

Also, if the old paths still exist: just use them instead.

Finally, always try to unlink/unpin before link/pin.

Fixes https://github.com/Homebrew/homebrew-core/issues/4918.
---
 Library/Homebrew/cmd/update-report.rb | 10 ++++++++--
 Library/Homebrew/cmd/update.sh        |  1 +
 Library/Homebrew/config.rb            | 14 +++++++++++---
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index fa82c875d4..653757a2e1 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -172,7 +172,11 @@ module Homebrew
     legacy_linked_kegs = HOMEBREW_LIBRARY/"LinkedKegs"
     return unless legacy_linked_kegs.directory?
 
-    legacy_linked_kegs.children.each {|f| Keg.new(f.realpath).link }
+    legacy_linked_kegs.children.each do |f|
+      keg = Keg.new(f.realpath)
+      keg.unlink
+      keg.link
+    end
     FileUtils.rm_rf legacy_linked_kegs
 
     legacy_pinned_kegs = HOMEBREW_LIBRARY/"PinnedKegs"
@@ -181,7 +185,9 @@ module Homebrew
     legacy_pinned_kegs.children.each do |f|
       pin_version = Keg.new(f.realpath).version
       formula = Formulary.factory(f.basename.to_s)
-      FormulaPin.new(formula).pin_at(pin_version)
+      pin = FormulaPin.new(formula)
+      pin.unpin
+      pin.pin_at(pin_version)
     end
     FileUtils.rm_rf legacy_pinned_kegs
   end
diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index ee6048ca8c..67b3699ed2 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -534,6 +534,7 @@ EOS
   if [[ -n "$HOMEBREW_UPDATED" ||
         -n "$HOMEBREW_UPDATE_FAILED" ||
         -n "$HOMEBREW_UPDATE_FORCE" ||
+        -d "$HOMEBREW_LIBRARY/LinkedKegs" ||
         (-n "$HOMEBREW_DEVELOPER" && -z "$HOMEBREW_UPDATE_PREINSTALL") ]]
   then
     brew update-report "$@"
diff --git a/Library/Homebrew/config.rb b/Library/Homebrew/config.rb
index 19ad7a7e54..31ac2d4350 100644
--- a/Library/Homebrew/config.rb
+++ b/Library/Homebrew/config.rb
@@ -18,10 +18,18 @@ HOMEBREW_LIBRARY = Pathname.new(ENV["HOMEBREW_LIBRARY"])
 HOMEBREW_SHIMS_PATH = HOMEBREW_LIBRARY/"Homebrew/shims"
 
 # Where we store symlinks to currently linked kegs
-HOMEBREW_LINKED_KEGS = HOMEBREW_PREFIX/"var/homebrew/linked"
+HOMEBREW_LINKED_KEGS = if (HOMEBREW_LIBRARY/"LinkedKegs").exist?
+  HOMEBREW_LIBRARY/"LinkedKegs"
+else
+  HOMEBREW_PREFIX/"var/homebrew/linked"
+end
 
-# Wehere we store symlinks to currently version-pinned kegs
-HOMEBREW_PINNED_KEGS = HOMEBREW_PREFIX/"var/homebrew/pinned"
+# Where we store symlinks to currently version-pinned kegs
+HOMEBREW_PINNED_KEGS = if (HOMEBREW_LIBRARY/"PinnedKegs").exist?
+  HOMEBREW_LIBRARY/"PinnedKegs"
+else
+  HOMEBREW_PREFIX/"var/homebrew/pinned"
+end
 
 # Where we store lock files
 HOMEBREW_LOCK_DIR = HOMEBREW_PREFIX/"var/homebrew/locks"