Fixed by http://hg.intevation.org/mercurial/crew/rev/80399b5b5f13
Dirkjan Ochtman <dirkjan@ochtman.nl>
bisect: allow revsets in addition to single revs (issue2360)

Fixed in 80399b5b5f13 (in crew).

$ hg bisect --skip "(1::4) - 4"
abort: unknown revision '(1::4) - 4'

$ hg bisect --skip "descendants(1) - descendants(4)"
abort: unknown revision 'descendants(1) - descendants(4)'!

In the Mozilla repository, we have several ranges of changesets that don't
compile at all (in some configurations).  I'd like to be able to --skip them
as a group.  For example, if rev 1 introduced bustage and rev 4 fixed it,
I'd like to be able to skip the changesets in between.