tests: use new main branch

Now that we clone "main" by default, use that for our local test.

Change-Id: Ib8420074bdfabfcb9d5252a3a0ecd3d852ca36e8
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/288422
Reviewed-by: Jonathan Nieder <jrn@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/tests/test_wrapper.py b/tests/test_wrapper.py
index e18ceb1..d22dc4e 100644
--- a/tests/test_wrapper.py
+++ b/tests/test_wrapper.py
@@ -402,8 +402,8 @@
     self.assertEqual('refs/heads/stable', rrev)
     self.assertEqual(self.REV_LIST[1], lrev)
 
-    rrev, lrev = self.wrapper.resolve_repo_rev(self.GIT_DIR, 'master')
-    self.assertEqual('refs/heads/master', rrev)
+    rrev, lrev = self.wrapper.resolve_repo_rev(self.GIT_DIR, 'main')
+    self.assertEqual('refs/heads/main', rrev)
     self.assertEqual(self.REV_LIST[0], lrev)
 
   def test_tag_name(self):