Fix mocker usage

test/test_version.py

@@ -3,7 +3,6 @@
 
 def test_version_fails_gracefully(mocker):
     target = 'pkg_resources.get_distribution'
-    with mocker.patch(target, side_effect=Exception()):
+    mocker.patch(target, side_effect=Exception())
     from flat_tree.__init__ import __version__
-
     assert __version__ == 'unknown'