Parent ordering

[Gustavo Niemeyer]

Greetings,

I'm currently working with David Allouche on the bzr support
of Launchpad, and one of the things we are wondering is if
the ordering of parents is meaningful. Can we trust that the
first parent in the list is always the Branch.last_revision()
at the commit moment?

Reading the code it looks like so (Commit._gather_parents),
but unfortunately we've not found any comments that specify
this as a design decision, rather than as a mere coincidence.

If ordering is indeed meaningful, we'll want to reproduce it
in Launchpad, and graph viewing algorithms (like the one in
bzrk) could also make use of it to improve the way the graph
is built.

Cheers,

-- 
Gustavo Niemeyer
http://niemeyer.net