rhg: allow specifying a changeset ID prefix
Differential Revision: https://phab.mercurial-scm.org/D9479
tests: update test-releasenotes-formatting.t with new exit codes
I didn't have the fuzzywuzzy package installed before, so I didn't
notice this test fail earlier (probably when I made
`check_incompatible_arguments` return `InputError`).
Differential Revision: https://phab.mercurial-scm.org/D9514
Added signature for changeset
1d5189a57405