Pass the mktemp prefix as an argument

Library/Homebrew/extend/fileutils.rb

@@ -5,15 +5,7 @@ module FileUtils extend self
 
   # Create a temporary directory then yield. When the block returns,
   # recursively delete the temporary directory.
-  def mktemp
-    # Prefer download_name if it is defined, for two reasons:
-    #  - The name attribute may be nil for resources that represent primary
-    #    formula downloads, in which case we want to use just the owner name.
-    #  - For resources that have a name defined, we want to use "owner--name"
-    #    instead of just "name"
-    prefix = download_name if respond_to?(:download_name)
-    prefix ||= name
-
+  def mktemp(prefix=name)
     # I used /tmp rather than `mktemp -td` because that generates a directory
     # name with exotic characters like + in it, and these break badly written
     # scripts that don't escape strings before trying to regexp them :(

Library/Homebrew/resource.rb

@@ -50,7 +50,7 @@ class Resource
   def stage(target=nil)
     fetched = fetch
     verify_download_integrity(fetched) if fetched.respond_to?(:file?) and fetched.file?
-    mktemp do
+    mktemp(download_name) do
       downloader.stage
       if block_given?
         yield self