diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index 177958266c..ba230bdec2 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -297,7 +297,8 @@ EOS
 
   if [[ -n "$HOMEBREW_NO_UPDATE_CLEANUP" ]]
   then
-    if [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" ]]
+    if [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" &&
+          ! "$INITIAL_BRANCH" =~ ^v[0-9]+\.[0-9]+\.[0-9]$ ]]
     then
       git checkout "$INITIAL_BRANCH" "${QUIET_ARGS[@]}"
     fi