We have darcs changes --last and --index which count in the global patch set. 
These switches don't interact with other matchers in the way that a lot of users
expect.  What these users really want is something like a --max-count switch
which filters AFTER the matchers have been applied and not simultaneously.

If we're clever, it may be possible to make darcs changes --max-count=1 faster
than darcs changes | head 1

See http://bugs.darcs.net/issue92

In my informal benchmarking, --last 1 was several times faster than darcs
changes | head 1 (or the xml equivalent); so that should be very possible.

The following patch updated the status of issue1437 to be resolved:

* resolve issue1437: Implement darcs changes --max-count. 
Ignore-this: c244ccdcd6e7c722b27f45310209cef2