From 07a00c234c2f0ed3387fc6508c2da21866f1e222 Mon Sep 17 00:00:00 2001
From: Alyssa Ross <hi@alyssa.is>
Date: Mon, 5 Sep 2016 11:20:19 +0100
Subject: [PATCH] Warn when changing branch on update

Closes #877
---
 Library/Homebrew/cmd/update.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index c0658aa4c7..9a9567101a 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -242,6 +242,15 @@ EOS
   INITIAL_BRANCH="$(git symbolic-ref --short HEAD 2>/dev/null)"
   if [[ "$INITIAL_BRANCH" != "$UPSTREAM_BRANCH" && -n "$INITIAL_BRANCH" ]]
   then
+
+    if [[ -z "$HOMEBREW_DEVELOPER" ]]
+    then
+      opoo <<EOS
+Checking out $UPSTREAM_BRANCH.
+Set HOMEBREW_DEVELOPER=1 to preserve branch when updating Homebrew.
+EOS
+    fi
+
     # Recreate and check out `#{upstream_branch}` if unable to fast-forward
     # it to `origin/#{@upstream_branch}`. Otherwise, just check it out.
     if git merge-base --is-ancestor "$UPSTREAM_BRANCH" "origin/$UPSTREAM_BRANCH" &>/dev/null