Upgrade testing_support library

bootstrap/deps.pyl

 # See README.md, there is a section about this file.
 #vim: ft=python:
 {
   'wheel': {
     'version': '0.24.0',
     'build': '0',
     'gs': 'c02262299489646af253067e8136c060a93572e3.tar.gz',
   },
 
   'argcomplete': {
@@ skipping 177 matching lines @@
     'version': '1.7.3',
     'build': '0',
     'repo': 'external/bitbucket.org/gutworth/six',
     'rev': 'e0898d97d5951af01ba56e86acaa7530762155c8',
     'implicit': True,  # Required by python_dateutil, webtest, uritemplate.
   },
   'testing_support': {
     'version': '0.1.8',
     'build': '0',
     'repo': 'infra/testing/testing_support',
-    'rev': '8da98d0f4a123099c4f9132a08b09055c35026dc',
+    'rev': 'ab9c80db669731ff1acdbe8f2f2a36433def4ba1',
   },
   'tzlocal': {
     'version': '1.2',
     'build': '0',
     'gs': 'd69c0f47b56c70523e60f6cf17f1f21c00b1ba6b.tar.gz',
   },
   'uritemplate': {
     'version': '0.6',
     'build': '0',
     'repo': 'external/github.com/uri-templates/uritemplate-py',
@@ skipping 14 matching lines @@
     'rev': '6581ebfe7e1f95b6f2e193723a9e0e1f02337851',
   },
   'WebOb': {
     'version': '1.4.1dev',
     'build': '0',
     'repo': 'external/github.com/Pylons/webob',
     'rev': 'ec67aba9d62d0e32dc5154c940a2214441bf0a9e',
     # 'implicit': True,  # Required by webtest
   },
 }