Andrew, I had this specific issue, with the 'NoSuchRevision' traceback in 1.14rc1.
I tried your first suggested workaround: I updated trunk, and tried branching again, but using a bzr+ssh:// url (lp:~mars/....). That caused bug 354036, 'AbsentContentFactory', to occur.
Next, I tried pulling from the sftp:// url, which worked perfectly.
So, pulling trunk/, and branching from the sftp:// URL should serve as a workaround for both this and bug 354036, without having to downgrade bzr.
Andrew, I had this specific issue, with the 'NoSuchRevision' traceback in 1.14rc1.
I tried your first suggested workaround: I updated trunk, and tried branching again, but using a bzr+ssh:// url (lp:~mars/....). That caused bug 354036, 'AbsentContentF actory' , to occur.
Next, I tried pulling from the sftp:// url, which worked perfectly.
So, pulling trunk/, and branching from the sftp:// URL should serve as a workaround for both this and bug 354036, without having to downgrade bzr.