Fix case of $0 truncating text due to being frozen

Fix failure on test "sets $0 while working"
This appears to be an OS dependent issue. I ran into this on
Ubuntu Linux 10.04 64bit on kernel 2.6.32-22
I do not know if this is an ideal solution, not did I come up
with it. I found the solution at:
http://www.ruby-forum.com/topic/187083#817010
but I do know that the tests now pass, so hopefully either this
gets incorporated, or triggers the creation of a better solution.

Author: chewbranca

lib/resque/worker.rb

@@ -456,6 +456,13 @@ def worker_pids
     # Procline is always in the format of:
     #   resque-VERSION: STRING
     def procline(string)
+      # Get around frozen $0
+      # Thanks to: http://www.ruby-forum.com/topic/187083#817010
+      $procline = $0
+      alias $PROC_LINE $0
+      alias $0 $procline
+      trace_var(:$0) {|val| $PROC_LINE = val}
+
       $0 = "resque-#{Resque::Version}: #{string}"
       log! $0
     end