git rebase master

[Florian Weimer]

On 05/28/2013 11:30 AM, Paolo Bonzini wrote:
> Il 27/05/2013 23:11, Adam Williamson ha scritto:
>> As soon as your
>> f19 build diverges from master at all, merging becomes inappropriate
>> (and probably impossible) and you should instead use 'cherry-pick'. It
>> helps to have at least a vague overview of how git is designed to be
>> used, and what is the actual _point_ of the commands you're using in the
>> intended git workflow.
>
> Interestingly, git itself is developed the other way round: you first do
> the fixes in the oldest applicable branch and "git merge" upwards (from
> f18 to f19, from f19 to master in the Fedora case).

That's because there's little support in VCS for backporting.  The VCS 
doesn't know if the new development in master is part of the fix, or 
unrelated new development.  The only system I've ever used which had 
some support for this was darcs, but more often than not, I had 
unintentional patch dependencies on new development I didn't want to 
backport, so it didn't work out that well.

The forward-porting approach has the risk that it stops before reaching 
master, so users will encounter regressions when updating.  And both 
approaches do not really mix that well because merging from the stable 
branch with cherry-picked and massages backports tends to conflict a lot.

Better tool support for backporting and the more general issue of patch 
stacks (like we have in RPM and Debian packages) is very desirable, but 
it's a really difficult problem.

-- 
Florian Weimer / Red Hat Product Security Team