Merge pull request #925 from jdavisp3/serial-fix

Fix off-by-one serial count (causing infinite loop for serial == 1).

lib/ansible/playbook/__init__.py

@@ -312,7 +312,7 @@ class PlayBook(object):
             # do N forks all the way through before moving to next
             while len(all_hosts) > 0:
                 play_hosts = []
-                for x in range(1, play.serial):
+                for x in range(play.serial):
                     if len(all_hosts) > 0:
                         play_hosts.append(all_hosts.pop())
                 serialized_batch.append(play_hosts)