FromPathLoader already calls expand_path

Library/Homebrew/formulary.rb

@@ -180,7 +180,7 @@ class Formulary
         # If name was a path or mapped to a cached formula
         f = FromPathLoader.new(name_or_path)
       elsif File.extname(name_or_path) == ".rb"
-        f = FromPathLoader.new(File.expand_path(name_or_path))
+        f = FromPathLoader.new(name_or_path)
       else
         f = StandardLoader.new(name_or_path)
       end