diff --git a/tests/utils/test_bzr_tags.py b/tests/utils/test_bzr_tags.py
index bc5f4ade0..14da67bc7 100644
--- a/tests/utils/test_bzr_tags.py
+++ b/tests/utils/test_bzr_tags.py
@@ -52,6 +52,9 @@ TAGS = [
     ['2.0', '2118'],
     ['2.1.0', '2119']
 ]
+# Depending on the repository, we sometimes have the 2.0.x tags in the repo too. They come up with a revision number of
+# "?", which I suspect is due to the fact that we're using shared repositories. This regular expression matches all
+# 2.0.x tags.
 TAG_SEARCH = re.compile('2\.0\.\d')