bzr upgrade sets looser permissions on backup.bzr than were on .bzr

[Steve McInerney]

Have a directory tree under bzr control. (website cms install, related config, images etc etc)
Some of the files managed are sensitive, and hence the entire .bzr tree is set to chmod o-rwx (0750 effectively).

Ran a bzr upgrade on the repository:
$ bzr upgrade --1.9

This upgraded nicely, but created a backup.bzr dir with looser permissions: 755:
drwxr-x--- 6 root root 4096 Mar 22 21:24 .bzr
drwxr-xr-x 6 root root 4096 Mar 22 21:22 backup.bzr

My 2c guess is that the upgrade is using the umask for file creation:
$ umask
0022

Which is fine and good in so far as following the set umask, but the behaviour is unexpected.

Ideally, I would have expected the permissions to be unchanged, or possibly restricted even further to just 0700.

Original version that created the repo was: Bazaar (bzr) 1.3.1
Version that did the upgrade was: Bazaar (bzr) 1.13

All done on a mostly stock (apart from a bzr PPA) Ubuntu Hardy install.