Bazaar 2.2 Windows installer - selftest broken

[John Barstow]

After installing Bazaar 2.2 "bzr selftest" is broken.

ERROR: No module named layout.test_custom

Appears that a subdirectory has gone missing from the bzr-svn tests directory.

After fixing that I get:

ImportError: cannot import name tests

Thrown by rewrite plugin (__init__.py line 54); I expect the tests
subdirectory has also gone walkabout.