via crew in main now.

here is patch i sent to mailing list.

mpm mentioned 'hg negate' which I like, too.

"backout" is my preference. It's commonly used (not just within Sun).

hg 'exclude' implies that history is modified to me. 'revoke' I could live with,
but seems odd.

Backing out a range of changesets should be possible, too, but using a simple
range (x:y) wouldn't do the right thing here, but instead two nodes and all
nodes topographically between them are meant.
The problem is how to specify this on the command line?
hg backout -r foo -r bar  (like with diff) might be confusing whether one wants
to exclude two revisions or all between them.
-r foo:bar  would be different from what e.g. hg log -r foo:bar will do (and
probably we want to have a feature to display nodes between two nodes in hg log,
too, so we can see which nodes gets excluded)
Maybe -r foo..bar or foo::bar?


Different topic: The name 'hg backout' doesn't look very intuitive for me, maybe
it is because I'm no native speaker.
Maybe one of:
hg reverse
hg cancel
hg override
hg suspend
hg repeal
But my favourites are:
hg exclude
hg revoke
hg zap

We first need the revert code in localrepo.py

Turns out, from talking on IRC, that Matt misunderstood what I was talking about.

I want to undo an earlier commit without losing the changes that have happened
since to any of the affected files.  By updating to the earlier rev, committing
an undo immediately after it, and doing a merge back to where I was, hg's
machinery will handle the merging for me.

I'll write this as an extension, then.  Manually doing a three-way merge is just
stupid, especially when doing a backout in the way I described makes the
revision history reflect what actually occurred.

NAK. I'll accept a change to revert that saves .orig files.

If you want to undo an earlier change, the revert command is often not a safe
way to do this.  The reason is that it restores a file in the working directory
to an earlier revision, but of course it does nothing with any changes to the
file that have happened between that revision and whatever revision the working
directory is currently at.

It would be good to add a backout command that undoes a change in a safer way. 
Here is how it sort of, kind of, ought to work:

hg backout -r77

If I were writing this as a shell script, this is what I'd do:

    remember current rev
    hg up -C $(rev to undo)
    hg revert -r $(parent of rev to undo)
    hg commit
    hg up -m $(previous rev)

If any changes happened since the rev to be undone, the hgmerge machinery should
either merge them properly, or drop us into a conflict resolution GUI.