Comment 5 for bug 308562

Here are some bugs that appear related (but I don't know whether they're strict dups, so not marking them as such):
  * Bug 242175: Better error message when merging into empty branch [requests a (better) error message, absent a real fix]
  * Bug 522740: Merging a branch into empty branch shows negative revision numbers in bzr log [a different symptom]
  * Bug 297768: switch does't work with empty branches
  * Bug 670291: Branching the 0. revision leads to weird behaviour ["switch" again]