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

On Thu, Sep 5, 2013 at 7:38 AM, John Keeping [off-list ref] wrote:

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

[snip]

quoted

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