From b0dfd2d435fe6f5617bd699be90d86ad84bced02 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Fri, 23 Sep 2016 11:26:24 +0100
Subject: [PATCH] update.sh: only update to semver tags.

Otherwise random e.g. `pr-123` tags may cause `brew update` to update
to the wrong version.
---
 Library/Homebrew/cmd/update.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index 5f082024d5..177958266c 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -217,7 +217,7 @@ merge_or_rebase() {
 
   if [[ "$DIR" = "$HOMEBREW_REPOSITORY" && -z "$HOMEBREW_NO_UPDATE_CLEANUP" ]]
   then
-    UPSTREAM_TAG="$(git tag --list --sort=-version:refname | head -n1)"
+    UPSTREAM_TAG="$(git tag --list --sort=-version:refname | grep '^[0-9]*\.[0-9]*\.[0-9]*$' | head -n1)"
   else
     UPSTREAM_TAG=""
   fi