Pin pyparsing to avoid warnings

Author: nedbat

tox.ini

@@ -19,6 +19,8 @@ deps =
     PyContracts==1.8.0
     unittest-mixins==1.4
     #-e/Users/ned/unittest_mixins
+    # Version 2.4.1.1 throws warnings all over: https://github.com/tox-dev/tox/issues/1375
+    pyparsing==2.4.0
     py26: unittest2==1.1.0
     py{27,33,34,35,36}: gevent==1.2.2
     py26: eventlet==0.21.0