Fix Formula#installed_prefix logic

Due to the precedence of "and" relative to "||", this was not working as
intended; but because #version influences #prefix, the outcome was still
correct. So we can simplify this method quite a bit, and take the
opportunity to share code with #prefix.

1 files changed, 4 insertions, 12 deletions

diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 34a6cf6ce..dab9726ed 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -99,17 +99,9 @@ class Formula
   end
 
   def installed_prefix
-    devel_prefix = unless devel.nil?
-      Pathname.new("#{HOMEBREW_CELLAR}/#{name}/#{devel.version}")
-    end
-
-    head_prefix = unless head.nil?
-      Pathname.new("#{HOMEBREW_CELLAR}/#{name}/#{head.version}")
-    end
-
-    if active_spec == head || head and head_prefix.directory?
+    if head && (head_prefix = prefix(head.version)).directory?
       head_prefix
-    elsif active_spec == devel || devel and devel_prefix.directory?
+    elsif devel && (devel_prefix = prefix(devel.version)).directory?
       devel_prefix
     else
       prefix
@@ -121,8 +113,8 @@ class Formula
     Keg.new(installed_prefix).version
   end
 
-  def prefix
-    Pathname.new("#{HOMEBREW_CELLAR}/#{name}/#{version}")
+  def prefix(v=version)
+    Pathname.new("#{HOMEBREW_CELLAR}/#{name}/#{v}")
   end
   def rack; prefix.parent end