scmutil: make shortest() respect disambiguation revset
The previous patch would let you use a shorter prefix if the prefix is
unique within a configured revset. However, that's not very useful if
there's no simple way of knowing what that shorter prefix is. This
patch adapts the shortest() template function to use the shorter
prefixes for nodes in the configured revset.
This is currently extremely slow, because it calculates the revset for
each call to shortest(). To make this faster, the next patch will
start caching the revset instance. Ideally we'd cache a prefix tree
instance instead.
Differential Revision: https://phab.mercurial-scm.org/D4038
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).