[MERGE][#90049] Don't require a working tree in cmd_annotate.

[Ian Clatworthy]

Lukáš Lalinský wrote:
> A fix for https://bugs.launchpad.net/bzr/+bug/90049 -- it simply uses
> the revision tree for path -> file_id lookup if no working tree is
> available.

bb: approve

I'll merge this.

Ian C.