zsh: fix `hg resolve` completion when in a subdirectory (
issue6067)
Differential Revision: https://phab.mercurial-scm.org/D5836
revset: add expectsize to check the size of a set
`expectsize(<set>, <int>)` revset fails if `<set>` is not exactly `<int>`
elements. `expectsize(<set>, <min>:<max>)` revset fails if `<set>` is not
exactly between `<min>` and `<max>` inclusive.
This then allows an alias for `hg next` to be `update -r one(children(.))`
with sane failure behavior, and also makes some other scripting tasks
a little less difficult.
(Summary from WeShouldDoThat)
Differential Revision: https://phab.mercurial-scm.org/D5813