perf: make perfmanifest and perfnodelookup work with revsets They were using repo[rev], which only works with a single symbol (e.g. "." or "my-bookmark"), not general revsets. Switch them to scmutil.revsingle() so they can also be used with e.g. ".^". I don't actually care about these commands, but I want to remove uses of repo[<string>]. Differential Revision: https://phab.mercurial-scm.org/D3083