shortest: use nodetree for finding shortest node within revset This speeds up `hg log -T '{shortest(node,1)}\n'` in my repo from 12s to 4.5s. That's very close to the 4.1s it takes without the disambiguation revset configured. My repo has 69.5k revisions, of which 550 were in the configured revset ("not public()"). Differential Revision: https://phab.mercurial-scm.org/D4120