Code review comment for lp:~vexo/bzr-webdav/bzr-webdav

Tests added via sub-classing DAVServer to exercise the different server behavior to make sure we handle it gracefully. QuirkyDAVServer/QuirkyTestingDAVRequestHandler should also serve decently as a place to stick any future tests for similar compatibility fixes without requiring a lot of work or exploding the number of tests we generate even further.