Merge pull request #7539 from jez/patch-1

Allow FormatError to take either String or Gem for source

(cherry picked from commit 5956bfb)

Author: deivid-rodriguez

lib/rubygems/package.rb

@@ -59,7 +59,7 @@ class FormatError < Error
 
     def initialize(message, source = nil)
       if source
-        @path = source.path
+        @path = source.is_a?(String) ? source : source.path
 
         message += " in #{path}" if path
       end