.arcconfig

rebase: only store collapse message once

The message is determined by the user passing --message or --log when
the rebase is started. There's no need to write it to a file for each
rebased commit; writing it once at the start of the rebase is enough.

Differential Revision: https://phab.mercurial-scm.org/D2712

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}