revlog: split the content verification of a node into a separate method
This will be used by LFS to tune what is skipped.
In the future, this could also be used by LFS to indicate which nodes tagged
with `skipread` are simply in need of a blob fetch, so that they can be done in
a batch later. (Currently, `skipread` also indicates censored data and errors.)
Additionally, it could be used to cache the sha1 hash value for each blob so
that large blobs don't need to be re-read and re-hashed if they are used by
multiple nodes.
Differential Revision: https://phab.mercurial-scm.org/D7710
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.