RE: Interesting git-format-patch bug

From: Olsen, Alan R <alan.r.olsen@intel.com>
Date: Nov 27, 2012, 20:31 UTC
Message-ID: <4B2793BF110AAB47AB0EE7B9089703854CA7C128@fmsmsx110.amr.corp.intel.com>
In-Reply-To: <50b4304c.EwQy4JquPwsUyMfZ%perryh@pluto.rain.com>

[Sorry for the top posting. Outlook is crap.]

You are correct. I should only get one copy of the patch on branch A. Branch B was modified after the merge and git-format-patch includes the original patch from the merge and a duplicate copy with the changed comments.  Note that this patch only has different comments. The body of the patch is exactly the same.

How gerrit mangles things is out of my control.  I would prefer that they cherry-pick instead of merges. I have to live with the bad choices of both gerrit and developers in this case.

I guess I will have to diagram out a better example of what is happening here.

-----Original Message-----
From: Perry Hutchison [mailto:perryh@pluto.rain.com] 
Sent: Monday, November 26, 2012 8:15 PM
To: gitster@pobox.com
Cc: git@vger.kernel.org; Olsen, Alan R
Subject: Re: Interesting git-format-patch bug

Junio C Hamano <gitster@pobox.com> wrote:

Show 19 quoted lines

> "Olsen, Alan R" <alan.r.olsen@intel.com> writes:
> > I found an interesting bug in git-format-patch.
> >
> > Say you have a branch A.  You create branch B and add a patch to it. 
> > You then merge that patch into branch A. After the merge, some other 
> > process (we will call it 'gerrit') uses annotate and changes the 
> > comment on the patch that exists on branch B.
> >
> > Now someone runs git-format-patch for the last n patches on branch 
> > A.  You should just get the original patch that was merged over to 
> > branch A.  What you get is the patch that was merged to branch A 
> > *and* the patch with the modified commit comment on branch B. 
> > (Double the patches, double the
> > clean-up...)
>
> As you literally have patches that do essentially the same or similar 
> things on two branches that was merged, you cannot expect to export 
> each individual commit into a patch and not have conflicts among them.  
> So I do not think there is no answer than "don't do that".

To me, this seems to miss Alan's point:  only one patch was merged to branch A, so git-format-patch applied to branch A should find only one patch.  It can be argued either way whether that one-patch report should include the gerrit annotations, but surely the application of gerrit on branch B, _after the merge to branch A has already been performed_, should not cause an additional patch to magically appear on branch A.