Re: Interesting git-format-patch bug

"Olsen, Alan R" [off-list ref] 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".

I think you could make your "some other process" that rewrites
commits to cull the duplicates out of the format-patch output,
though.  Each output file identifies what commit object the patch
came from, and your "some other process" that rewrote the commits
ought to know which commit updated which other commit did, which is
the piece of information needed to remove duplicates that format-patch
does not have.