context: stop catching RepoLookupError from namespace.singlenode() As pointed out by Yuya, the RepoLookupError was there for catching errors from repo.branchtip(). However, since 885c0290f7d5 (localrepo: add ignoremissing parameter to branchtip, 2014-10-16), that should no longer happen. I think it should now be an error if a namespace raises a RepoLookupError, so we propagate the exception up and and make it easy to fix, rather than trying to interpret the changeid as nodeid prefix and raise a general "unknown revision '...'" error. I also don't think we should catch FilteredLookupError and LookupError from the changelog.rev() call, for the same reason as above: If a namespace returns a node that doesn't exist, we should provide a more helpful exception than "unknown revision '...'". Differential Revision: https://phab.mercurial-scm.org/D3145