Match shorter

before:
without_list_prefix("[ruby-dev:1] Re: [ruby-list:3486] Re: eval with dynamic binding [Re: meta programming features]")
 #=> ""

after:
without_list_prefix("[ruby-dev:1] Re: [ruby-list:3486] Re: eval with dynamic binding [Re: meta programming features]")
 #=> "Re: [ruby-list:3486] Re: eval with dynamic binding [Re: meta programming features]"

Author: amatsuda

app/helpers/messages_helper.rb

@@ -1,6 +1,6 @@
 module MessagesHelper
     def without_list_prefix(subject)
-        subject.sub(/^\[.+\]\s*/, '')
+        subject.sub(/^\[.+?\]\s*/, '')
     end
 
     MARGIN = 50