Support for specific revisions of bzr branches

[Tom Haddon]

bzr url specs don't have specific revnos implemented in cm.py as yet. They should use a revno url parameter - e.g.

./tree_root branch_location1;revno=XXX
./tree_root/subdir branch_location2;revno=XXX

[Robert Collins (lifeless)]

Config-manager already supports this, its a VCS specific code path. Just needs one added for the VCS you're interested in.

[Elliot Murphy (statik)]

Taking this per discussion with Robert.

[Elliot Murphy (statik)]

This is needed in order to stabilize our sourcedeps so that we can do synchronized orderly upgrades of sourcedeps.

[Elliot Murphy (statik)]

I have a patch that works and the branch is proposed for merging.

[Elliot Murphy (statik)]

I have done all I can on this, it's now waiting on an RT for pqm config to be updated. Bumping to the w11 milestone since the RT will likely not be done this week.