fix erroneous pruning of living workers

Author: Tom Brow

lib/resque/worker.rb

@@ -470,7 +470,7 @@ def pid
     # Returns an array of string pids of all the other workers on this
     # machine. Useful when pruning dead workers on startup.
     def worker_pids
-      `ps -A -o pid,command | grep [r]esque | grep -i "resque-web"`.split("\n").map do |line|
+      `ps -A -o pid,command | grep [r]esque | grep -v "resque-web"`.split("\n").map do |line|
         line.split(' ')[0]
       end
     end