[MERGE] get_file_mtime tests

[John Arbash Meinel]

This patch just cleans up the existing 'get_file_mtime()' test, and adds
a couple more tests for WorkingTrees to make sure they properly handle
files which have been moving around.

I wrote them while trying to track down:
https://bugs.launchpad.net/bzr/+bug/103870

But it turns out the bug is specifically in the diff code (it is passing
a path for 'old', when a file is just 'modified', not realizing the file
isn't at that path, because the containing directory has been renamed.)

I'm working on a real fix for the other, but I figured these tests were
good to have.

John
=:->
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: get_file_mtime_tests.patch
Url: https://lists.ubuntu.com/archives/bazaar/attachments/20070411/1a326c94/attachment.diff