Merge pull request apache#31 in TP/incubator-airflow from feature/DEV…

…OPS-8865 to develop

* commit 'c41e6d496d0f74b8f69a35e25f061e6d7b879c71':
  DEVOPS-8865 - Upgraded Raven version to latest 6.9.0, particularly because it installs contextlib2 that was missing in 5.32.0

setup.py

@@ -157,7 +157,7 @@ def write_version(filename=os.path.join(*['airflow',
     'filechunkio>=1.6',
 ]
 samba = ['pysmbclient>=0.1.3']
-sentry = ['raven[flask]==5.32.0']
+sentry = ['raven[flask]==6.9.0']
 slack = ['slackclient>=1.0.0']
 statsd = ['statsd>=3.0.1, <4.0']
 vertica = ['vertica-python>=0.5.1']