Bug 1471622 - Fix mozfile's test_extract.py under Python 3.5; r=davehunt

MozReview-Commit-ID: 5c8SoMMpv70

--HG--
extra : rebase_source : 65717f1f056d43588b4df59ea765a7ec2e2657c0

testing/mozbase/mozfile/tests/manifest.ini

@@ -1,7 +1,6 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
 [test_extract.py]
-skip-if = python == 3
 [test_load.py]
 skip-if = python == 3
 [test_move_remove.py]

testing/mozbase/mozfile/tests/test_extract.py

@@ -112,14 +112,16 @@ class TestExtract(unittest.TestCase):
         os.write(fd, b'This is not a zipfile or tarball')
         os.close(fd)
         exception = None
+
         try:
             dest = tempfile.mkdtemp()
             mozfile.extract(filename, dest)
-        except Exception as exception:
-            pass
+        except Exception as exc:
+            exception = exc
         finally:
             os.remove(filename)
             os.rmdir(dest)
+
         self.assertTrue(isinstance(exception, Exception))
 
     # utility functions