bzr fails on relative colocated branch location created by breezy

[Martin Packman]

A native colocated branch created by breezy (using `brz switch -b crc_asul` for instance) causes subsequent bzr operations on the branch to fail

$ bzr status
bzr: ERROR: Not a branch: "/home/martin/brz/,branch=crc_asul/".

$ bzr info
Dangling branch reference (format: 2a)
Location:
  checkout of branch: ,branch=crc_asul
          repository: .

This is due to the branch location now being recorded as a pseudo-relative path:

.bzr/branch/location
  ,branch=crc_asul

Whereas it used to be an absolute url:
  file:///home/martin/brz,branch=crc_asul