`run` and `rehearse` always fetched migrate_v016.py from GitHub, so a mail
server with no route out could not be migrated at all - an air-gapped host,
or a clone deliberately cut off so it cannot renew certificates or deliver
queued mail for the domains it was copied from. --migration-script takes a
local copy instead, still checked against --migration-script-sha256 when one
is pinned.
Found while staging a production clone for a dress rehearsal: the clone has
no route out on purpose, and that is exactly the property that stops a copy
of a live mail server doing something in the real world.
jcoffey-dev
0739866c14