Merging unrelated branches with a multi-parent revision

[James Westby]

Hi all,

I'd like to know how to solve the following issue.

We have a process which automatically creates branches for 
package-import.ubuntu.com, and we are extending it to include Debian
branches. In some cases the Debian and Ubuntu branches may not share any
history that we can infer, meaning that the branches will not have
a common ancestor.

However, someone may still wish to merge the branches. However, it
would need to be with a multi-parent revision, rather than a 
cherry-pick, so that the branches can be merged again later using the
merge information.

File ids aren't a problem, as we can make sure they match where 
necessary, it's just the mechanism to make the multi-parent revision.

It's possible to do this through the API, but I don't know a way to do 
it through the command line. I could therefore write a new command to
do it, but I would prefer to not have to.

Is it possible without using the API directly? bzr.dev contains merges
of a couple of external things, how were they achieved?

Thanks,

James