diff --git a/common/travis/changed_templates.sh b/common/travis/changed_templates.sh
index 3c8acf78763..534cd97a12b 100755
--- a/common/travis/changed_templates.sh
+++ b/common/travis/changed_templates.sh
@@ -6,7 +6,9 @@ PATH="/usr/libexec/chroot-git:$PATH"
 
 tip="$(git rev-list -1 --parents HEAD)"
 case "$tip" in
+	# This is a merge commit, pick last parent
 	*" "*" "*) tip="${tip##* }" ;;
+	# This is a non-merge commit, pick itself
 	*)         tip="${tip%% *}" ;;
 esac