git hash is included in build exactly when it is not useful

[slingamn]

goreleaser sets the git hash for builds, so you get:

:oragono.test 002 b :Your host is oragono.test, running version oragono-2.0.0-8fd326fd33f29f19c8c9aa121b9b4e9ebf931879

But goreleaser requires a tag, so the hash is actually redundant in this case: the revision is necessarily the tagged one. (Granted, there could be discrepancies between the published tag and the one the release was built from, but this seems unlikely to arise in practice).

Meanwhile, regular builds from the git master branch simply say 2.1.0-unreleased here.

Can we switch these around?

[slingamn]

Relevant: golang/go#29228