Tighten up clone locking Add a lock on the destination, expand comment on source lock

Clean up local clone file list We now use an explicit list of files to copy during clone so that we don't copy anything we shouldn't.

Rewrite copytree as copyfiles This inverts the logic of copytree to allow copying single files at the top level.

Redo local clone hgrc fix We shouldn't copy hgrc on a local clone, nor localtags. Behavior should be identical to a remote clone.

Write out hgrc properly. Previously, we simply appended to the hgrc file, which meant that it ended up containing multiple "paths" sections. Now, we only modify "paths.default".

patchbomb: continue if we can't import readline.

Get test-commit to exit cleanly.

Commit date validation: more stringent checks, more useful error messages.

revlog: raise informative exception if file is missing.

Minor cleanups.