My suggestion is to _locally_ use:

http://wiki.mozilla.org/Using_Mercurial_locally_with_CVS

To keep up to date with changes to 1.9.

Then pull from that local repo into your Hg Tree.

If you do not want to host all of mozilla on MozDev you can simply use hg outgoing and similar to find out what differs between your mozilla tree and your hg cvs copy.

You can then write a python script (such as mozilla-centrals client.py) to checkout Mozilla from 1.9; apply your specific patches and checkout the verbosio code from whatever type of repository you want to you.

The HgBook I have been reading online is quite good (a few minor errors I have found, that I have notified the author on) but all in all, everything is great! http://hgbook.red-bean.com

You can add comments to your hg patch with mq by doing |hg qrefresh -e| ;)

With that said, I think a case can be made to maintain the cvs-trunk-mirror (for those who have to backport branch patches at least). jst has the scripts, so it's likely you just need to find someone to push the changes who has commit rights. This is all a lot of handwaving, but talking with bsmedberg on irc the other day, this didn't seem too difficult to do.

cvs-trunk-mirror only really matters if it's important to keep individual checkins as changesets. If it isn't, then you could just import the 1.9 code into your own Hg repo, and periodically update by just copying in the new code. You could then maintain your own changes in either a separate branch, and merge from 1.9 over to your branch, or use mq and keep it as a patchset, although that seems kind of silly.

This isn't related to the subject of your post, but rather its format: on planet, it looks like your post ends after the one-sentence parenthetical paragraph, with no indication that there’s more to read on-site. If you don’t want to include a full-content feed, could you please include a “More” notice at the point where the post is otherwise chopped off? Thanks!

I think quilt does what you want, although I've never used it myself.

You might want to take a look at the pbranch extension for Mercurial:

http://arrenbrecht.ch/mercurial/pbranch/