Enable flake8-bugbear, but disable most checks. (#9499)

* Adds B00 to ignored checks.
* Fixes remaining issues.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/unittest.py b/tests/unittest.py
index ca7031c724..224f037ce1 100644
--- a/tests/unittest.py
+++ b/tests/unittest.py
@@ -140,7 +140,7 @@ class TestCase(unittest.TestCase):
             try:
                 self.assertEquals(attrs[key], getattr(obj, key))
             except AssertionError as e:
-                raise (type(e))(e.message + " for '.%s'" % key)
+                raise (type(e))("Assert error for '.{}':".format(key)) from e
 
     def assert_dict(self, required, actual):
         """Does a partial assert of a dict.