Is the branch you are merging from a stacked branch? If so, was that branch ever pushed to with bzr 1.14rc1 or older?
If both of those are true, this is bug #354036. See that bug for some workarounds (and detailed analysis if you're curious).
Is the branch you are merging from a stacked branch? If so, was that branch ever pushed to with bzr 1.14rc1 or older?
If both of those are true, this is bug #354036. See that bug for some workarounds (and detailed analysis if you're curious).