bzr annotate gives revision numbers of the form a.b.c where a is the revision that was branched off; for our workflow it's more interesting to know in which revision this changed was merged back into the current repo. Can I get bzr to tell me this info?
You can use revision prefix mainline:, see bzr help revisionspec for details.
For example,
bzr revno -r 1.2.3
prints 1.2.3, but
bzr revno -r mainline:1.2.3
prints revision number for revision that merged 1.2.3.