[PATCH 0 of 2 stable] remove copyfile usage in bookmarks and move copystat hack into record

[Brodie Rao]

Here's an updated series based on your feedback on IRC.

This series only fixes bookmarks and moves record's shutil.copystat
hack out of util.copyfile. It doesn't address the general issue of
copyfile failing when the user running hg doesn't own the target file,
which I don't have a good solution for.