diff --git a/gallery_dl/version.py b/gallery_dl/version.py
index 5defc88e..680765fe 100644
--- a/gallery_dl/version.py
+++ b/gallery_dl/version.py
@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
-__version__ = "0.9.1"
+__version__ = "1.0.0-dev"
diff --git a/test/test_cookies.py b/test/test_cookies.py
index faa1817d..5d069fbe 100644
--- a/test/test_cookies.py
+++ b/test/test_cookies.py
@@ -69,7 +69,7 @@ class TestCookiejar(unittest.TestCase):
         with mock.patch.object(log, "warning") as mock_warning:
             cookies = extractor.find("test:").session.cookies
             self.assertEqual(len(cookies), 0)
-            mock_warning.assert_called_once()
+            self.assertEqual(mock_warning.call_count, 1)
             self.assertEqual(mock_warning.call_args[0][0], "cookies: %s")
             self.assertIsInstance(mock_warning.call_args[0][1], exc)
 
diff --git a/test/test_extractors.py b/test/test_extractors.py
index 47bfe7ad..274ee78c 100644
--- a/test/test_extractors.py
+++ b/test/test_extractors.py
@@ -58,7 +58,7 @@ skip = [
     "exhentai", "kissmanga", "mangafox", "dynastyscans", "nijie",
     "archivedmoe", "archiveofsins", "thebarchive",
     # temporary issues
-
+    "twitter",
 ]
 # enable selective testing for direct calls
 if __name__ == '__main__' and len(sys.argv) > 1: