Prefer HEAD version if its installed

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Homebrew/brew.h.rb

@@ -199,7 +199,7 @@ def info f
     kids=f.prefix.parent.children
     kids.each do |keg|
       print "#{keg} (#{keg.abv})"
-      print " *" if f.prefix == keg and kids.length > 1
+      print " *" if f.installed_prefix == keg and kids.length > 1
       puts
     end
   else
@@ -258,7 +258,7 @@ def cleanup name
   if f.installed? and formula_cellar.directory?
     kids = f.prefix.parent.children
     kids.each do |keg|
-      next if f.prefix == keg
+      next if f.installed_prefix == keg
       print "Uninstalling #{keg}..."
       FileUtils.rm_rf keg
       puts

Library/Homebrew/formula.rb

@@ -98,11 +98,20 @@ class Formula
 
   # if the dir is there, but it's empty we consider it not installed
   def installed?
-    return prefix.children.length > 0
+    return installed_prefix.children.length > 0
   rescue
     return false
   end
 
+  def installed_prefix
+    head_prefix = HOMEBREW_CELLAR+@name+'HEAD'
+    if @version == 'HEAD' || head_prefix.directory?
+      head_prefix
+    else
+      prefix
+    end
+  end
+
   def path
     self.class.path name
   end