localrepo: delete obsolete comment about `prefix in repo` raising exception We dropped support for `prefix in repo`, where `prefix` is a hex prefix, in 8b86acc7aa64 (context: drop support for looking up context by ambiguous changeid (API), 2018-04-28), after having deprecated it a while before that. These days you get a `ProgrammingError` instead if you pass in a short nodeid. Differential Revision: https://phab.mercurial-scm.org/D9599