Re: Fwd: What is the best way to backport a feature?

[Johannes Sixt <j6t@kdbg.org>]

[please keep the Cc list]

On Sonntag, 29. November 2009, Peter Weseloh wrote:
> But on the other hand the intermediate merges from the Mainline make
> for much simpler merges, right?.
> If merging is done only when Feature_A is ready it might become a real
> pain. It might take several month to complete it and the mainline
> might have changed a lot.

Incidentally, Junio has blogged about this just the other day:

http://gitster.livejournal.com/42247.html

Basically, as soon as you merge Mainline into Feature_A, you change the topic 
of Feature_A from "Feature for Release_1.0" to "Feature for this Mainline". 
Clearly, this topic is not suitable for Release_1.0 anymore.

There is a way around this that doesn't sacrifice the topic-oriented nature of 
the branch: You keep developing Feature_A as planned for Release_1.0 and when 
you notice that merging this feature to Mainline will become increasingly 
complex, you fork off a new branch Feature_A_for_Release_2.0 from Mainline 
and merge Feature_A into this new branch:

   o--o--o                    Release_1.0
  /    \  \
 o-o-o--o--o-o-o-o-X-o---o--o Mainline
      \             \
       F1            o--o     Feature_A_for_Release_2.0   
        \           /  /
         F2--------F3-F4      Feature_A

The fork point X must be in Release_2.0.

-- Hannes