Better cache names for accessory-formula

Because formula don't get named unless the brew kit instantiates them accessory formula were getting named "__UNKNOWN__". Which sucks.

This isn't ideal for me as I made the naming use @name and @version to ensure unique naming. Now it is possible to have name clashes in the cache. So I need to solve it better at some point.

Library/Homebrew/download_strategy.rb

@@ -18,14 +18,18 @@
 class AbstractDownloadStrategy
   def initialize url, name, version
     @url=url
-    @unique_token="#{name}-#{version}"
+    @unique_token="#{name}-#{version}" unless name.to_s.empty? or name == '__UNKNOWN__'
   end
 end
 
 class HttpDownloadStrategy <AbstractDownloadStrategy
   def fetch
     ohai "Downloading #{@url}"
-    @dl=HOMEBREW_CACHE+(@unique_token+ext)
+    if @unique_token
+      @dl=HOMEBREW_CACHE+(@unique_token+ext)
+    else
+      @dl=HOMEBREW_CACHE+File.basename(@url)
+    end
     unless @dl.exist?
       curl @url, '-o', @dl
     else

Library/Homebrew/formula.rb

@@ -254,8 +254,8 @@ private
   end
 
   def validate_variable name
-    v=eval("@#{name}")
-    raise "Invalid @#{name}" if v.nil? or v.empty? or v =~ /\s/
+    v=eval "@#{name}"
+    raise "Invalid @#{name}" if v.to_s.empty? or v =~ /\s/
   end
 
   def method_added method