purge: simplify safety net for case mangling filesystems
Relying on the exact return of statwalk would cause us to abort
when there was at least one tracked file inside an ignored directory.
This patch forces an extra walk of the whole working directory even
on sane filesystems, where it wouldn't be needed.
Fixes
issue621.
Fix dir-changed-to-file updates on clean workdir.
Workaround for dir-changed-to-file updates mentioned
in rev
7a64931e2d76 doesn't actually work since tests
introduced in mentioned changeset prevented dirstate
updates even if working directory updates succeded.
Make tests more relaxed for dirstate operations
not directly accessible from cli. See also
issue660.
While here, move _dirs existance check from _decpath()
to _changepath() for unification.