Code review comment for lp:~mwhudson/launchpad/bzr-2.1b3-support

Hello.

This branch moves us to bzr 2.1b3. There are a few changes:

 * bzrlib now attempts to enforce that tests don't read out of their isolated area on the file system, which breaks many many launchpad tests.
   * I just scattered calls to disable_directory_isolation() around where it was needed, which perhaps isn't very awesome but it works.
 * $BZR_HOME and $HOME tend to be unicode now in TestCaseWithMemoryTransport tests (bzr bug 464174).
   * One test didn't need to subclass this class.
   * TestPullerMasterIntegration hacks around this.
 * WorkingTree.merge_from_branch now needs a force argument to create a revision with >2 parents, just like the CLI.

Cheers,
mwh