diff --git a/tests/git_common_test.py b/tests/git_common_test.py
index e6e2f83447..856f5374fb 100755
--- a/tests/git_common_test.py
+++ b/tests/git_common_test.py
@@ -36,6 +36,7 @@ class GitCommonTestBase(unittest.TestCase):
     import git_common
     cls.gc = git_common
     cls.gc.TEST_MODE = True
+    os.environ["GIT_EDITOR"] = ":" # Supress git editor during rebase.
 
 
 class Support(GitCommonTestBase):