tox tests: pin test requirement versions

Tests once again randomly broke due to a PyPi release.
This makes req versions explicit so they only change deliberately.

1 files changed, 1 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index 643fa774d..1b02234e5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,7 @@ skip_install=True
 deps =
     -rrequirements.txt
     -rtest-requirements.txt
-    py35-flake8: flake8-bugbear
+    py35-flake8: flake8-bugbear==17.3.0
 
 commands =
     unit: pip install -e utils