todo:
+- generate deltas rather than fulltexts when creating file id maps
- BzrDir.create_branch() should set the revision id to NULL_REVISION
- avoid extra connect in logwalker?
- free memory! (#54253)
+- tests for setting svk:merge from .bzr checkout
+- tests for http-specific SvnRaTransport._request_path() code
- more blackbox tests
- svn-import without scheme specified should guess
+ - bzr missing
- transform file ids in workingtree in svn-upgrade
- support tags (#81102)
- more efficient implementation of get_revision_delta() to speed up bzr log -v