clone: cleanup the "cleanup dir" logic used during local clone
With the previous code, there was a small windows were we could delete too much
data. This should no longer be the case.
(This is an opportunity improvement while looking at something next to that.)
Differential Revision: https://phab.mercurial-scm.org/D10840
== New Features ==
* `hg config` now has a `--source` option to show where each
configuration value comes from.
== Default Format Change ==
These changes affects newly created repositories (or new clone) done with
Mercurial 5.8.
== New Experimental Features ==
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==