Bidirectional syncing on parallel branches

[Stefan Monnier]

How do people handle bidirectional syncing between two branches that are
meant to be different (ie. when properly sync'd there are still
differences between the two trees)?

The way I imagine it working would be something like a new command:

   bzr set-artificial-common-ancestor <otherbranch>

which would not change anything to the content of the tip of the current
branch not of the otherbranch, but it would add to the history some info
saying that those two tips should be considered as "a common ancestor"
in future merges.

So when a merge takes place later on, it will use this
artificial-common-ancestor to compute the diff to apply (that'd be
a diff4 style merge, I guess, but I could live with a simpler
diff+patch) and will mark the resulting revision as a new
artificial-common-ancestor.

So if one later on wants to install a change on a branch that should be
visible to the other branch, one can simply commit the change and then say

   bzr set-artificial-common-ancestor <otherbranch>

again.  Not sure how easy/convenient it would be to implement and even
less sure what the semantics of such an artificial-common-ancestor would
be when other branches come into play.


        Stefan