Re: [PATCH 0/3] Reject non-ff pulls by default

From: John Szakmeister <john@szakmeister.net>
Date: Sep 5, 2013, 12:37 UTC
Message-ID: <CAEBDL5U2Y-dxtGyDTW+C-SseSpuF40BNMW3oZDnfzRx8KxG7fA@mail.gmail.com>
In-Reply-To: <20130905113822.GF2582@serenity.lan>

On Thu, Sep 5, 2013 at 7:38 AM, John Keeping <john@keeping.me.uk> wrote:

> On Thu, Sep 05, 2013 at 07:01:03AM -0400, John Szakmeister wrote:

[snip]

Show 6 quoted lines

>> So what I really want isn't quite rebase.  I'm not sure any of the
>> proposed solutions would work.  It'd be really nice to replay only the
>> mainline commits, without affecting commits introduced from a topic
>> branch.
>
> Does "git rebase --preserve-merges" do what you want here?

No, unfortunately, it does not. If the topic branch was not based on the current tip of master, "git rebase --preserve-merges" will rebase the commits of the topic branch as well. So this:

       Q -- R -- S     (topic)
     /            \
    A -- B ------- D   (master)

Will become this after "git rebase --preserve-merges @{u}":

                 Q' -- R' -- S'    (topic')
               /              \
    A -- B -- C -------------- D'  (master)

It's unfortunate for a couple of reasons. First, we don't want Q, R, and S rebased--we just want the merge replayed. Secondly, it gets more confusing because Q, R, and S were rebased, but the topic branch wasn't actually touched. So topic still contains Q, R, and S, but master now contains Q', R', and S'. What we actually want is:

       Q -- R -- S     (topic)
     /            \
    A -- B -- C -- D'  (master)

HTH!

-John