copies: add a devel debug mode to trace what copy tracing does
Mercurial can spend a lot of time finding renames between two commits. Having
more information about that process help to understand what makes it slow in
an individual instance. (eg: many files vs 1 file, etc...)
Mercurial's documentation is kept in reStructuredText format, which is
a simple plain text format that's easy to read and edit:
http://docutils.sourceforge.net/rst.html
It's also convertible to a variety of other formats including standard
UNIX man page format and HTML. You'll need to install Docutils:
http://docutils.sourceforge.net/
Use the Makefile in this directory to generate the man and HTML pages.