Comment 13 for bug 375898

@Kristian: I know merge-into has bugs, I stated it in comment #11, what I was trying to say was:

if the merge-into bugs were fixed, then using it will be a workaround for this (bug #373898) bug.

The workaround I'm suggesting is not using merge-into, for your case it would be:
    cd pbxt
    bzr mkdir temporary-subdir
    bzr mv `ls|grep -v temporary-subdir` temporary-subdir/ # watch for unknowns here but that's the idea
    bzr commit
    cd ../maria
    bzr merge -r0.. ../pbxt
    bzr mv temporary-subdir storage/pbxt
    bzr commit

From there the merges from pbxt shouldn't crash, but 'temporary-subdir' has to stay (at least until either this bug is fixed or merge-into is fixed or both) so you may want to use another name :-/