tests: use inline Python for revlog test
`hg debugdata` will soon stop accepting the raw path to a revlog file.
Adjust a test accordingly.
The changed test is for a security bug. So this should be reviewed
with scrutiny.
Differential Revision: https://phab.mercurial-scm.org/D4356
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.