Updated from global requirements

Change-Id: Icd26cb6d2525ff1736923c39e9c64eb12f6d39b6

Author: OpenStack Proposal Bot

requirements.txt

@@ -1,7 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-pbr>=2.0.0 # Apache-2.0
+pbr!=2.1.0,>=2.0.0 # Apache-2.0
 six>=1.9.0 # MIT
 
 Babel!=2.4.0,>=2.3.4 # BSD