update opt for renamed formula

After the formula gets renamed oldname opt is created and
it points to the linked keg. However if we then upgrade newname
oldname opt still points to the same keg it pointed before upgrade.
The commit fixes this behaviour thus that oldname opt links at the
same keg opt point.

Library/Homebrew/cmd/uninstall.rb

@@ -18,15 +18,9 @@ module Homebrew
           # Remove every symlink that links to keg, because it can
           # be left by migrator
           links.each do |link|
-            old_opt = HOMEBREW_PREFIX/"opt/#{link.basename}"
             if link.exist? && link.realpath == keg.rack.realpath
               old_cellars << link
             end
-
-            if old_opt.symlink? && old_opt.realpath.to_s == keg.to_s
-              old_opt.unlink
-              old_opt.parent.rmdir_if_possible
-            end
           end
 
           keg.unlink
@@ -52,13 +46,6 @@ module Homebrew
         name = rack.basename
 
         links.each do |link|
-          old_opt = HOMEBREW_PREFIX/"opt/#{link.basename}"
-          if old_opt.symlink? && old_opt.exist? \
-              && old_opt.realpath.parent == rack.realpath
-            old_opt.unlink
-            old_opt.parent.rmdir_if_possible
-          end
-
           link.unlink if link.exist? && link.realpath == rack.realpath
         end
 

Library/Homebrew/keg.rb

@@ -183,6 +183,7 @@ class Keg
     path.rmtree
     path.parent.rmdir_if_possible
     remove_opt_record if optlinked?
+    remove_oldname_opt_record
   end
 
   def unlink
@@ -256,6 +257,14 @@ class Keg
     path.find(*args, &block)
   end
 
+  def oldname_opt_record
+    @oldname_opt_record ||= if (opt_dir = HOMEBREW_PREFIX/"opt").directory?
+      opt_dir.subdirs.detect do |dir|
+        dir.symlink? && dir != opt_record && path.parent == dir.resolved_path.parent
+      end
+    end
+  end
+
   def link(mode = OpenStruct.new)
     raise AlreadyLinkedError.new(self) if linked_keg_record.directory?
 
@@ -330,9 +339,22 @@ class Keg
     ObserverPathnameExtension.total
   end
 
+  def remove_oldname_opt_record
+    return unless oldname_opt_record
+    return unless oldname_opt_record.resolved_path == path
+    @oldname_opt_record.unlink
+    @oldname_opt_record.parent.rmdir_if_possible
+    @oldname_opt_record = nil
+  end
+
   def optlink(mode = OpenStruct.new)
     opt_record.delete if opt_record.symlink? || opt_record.exist?
     make_relative_symlink(opt_record, path, mode)
+
+    if oldname_opt_record
+      oldname_opt_record.delete
+      make_relative_symlink(oldname_opt_record, path, mode)
+    end
   end
 
   def delete_pyc_files!