From cc632acd07d0884d51c5de414fcabd6e5f856fd2 Mon Sep 17 00:00:00 2001 From: Martin Afanasjew Date: Sun, 13 Dec 2015 00:25:53 +0100 Subject: [PATCH] update: avoid unnecessarily recreating 'master' This only affects the behavior of `brew update` while being on a branch `feature` that doesn't track the upstream branch. For simplicity, the upstream branch is assumed to be called `master` (`@upstream_branch` in the code). Consider the following simplified commit history: master origin/master (current state of remote) | | A---B---C---D---E---F \ G---H---I | feature (HEAD) If `origin/master` is equal to `master` and also points at commit `C`, then `brew update` will update both `master` and `origin/master` to `F` and report on the changes in the range `C..F`. However, if `origin/master` is equal to `E` because some commits have been already fetched with `git fetch origin`, then `brew update` will recreate `master` from `origin/master` and then pull in the commits from the remote to update both to `F`. Because `master` gets recreated from a younger `origin/master`, the report will only contain changes from the range `E..F` (thus omitting the changes from `C..E`). This commit adjusts the logic to not recreate `master` if it can be safely fast-forwarded to `origin/master` (the common case). This fixes the problem from the second scenario and again reports on the desired range `C..F`. Closes Homebrew/homebrew#46951. Signed-off-by: Martin Afanasjew --- Library/Homebrew/cmd/update.rb | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/Library/Homebrew/cmd/update.rb b/Library/Homebrew/cmd/update.rb index 08062e15b5..9e2541434e 100644 --- a/Library/Homebrew/cmd/update.rb +++ b/Library/Homebrew/cmd/update.rb @@ -247,7 +247,13 @@ class Updater end if @initial_branch != @upstream_branch && !@initial_branch.empty? - safe_system "git", "checkout", "--force", "-B", @upstream_branch, "origin/#{@upstream_branch}", *@quiet_args + # Recreate and check out `#{upstream_branch}` if unable to fast-forward + # it to `origin/#{@upstream_branch}`. Otherwise, just check it out. + if system("git", "merge-base", "--is-ancestor", @upstream_branch, "origin/#{@upstream_branch}") + safe_system "git", "checkout", "--force", @upstream_branch, *@quiet_args + else + safe_system "git", "checkout", "--force", "-B", @upstream_branch, "origin/#{@upstream_branch}", *@quiet_args + end end @initial_revision = read_current_revision