When adding Avatar email-hash pairs we simply want the DB table to
represent a Set. We don't care if the hash-pair is already present,
so we just simply Insert and ignore the error.
Unfortunately this seems to cause some DBs to log the duplicate
insert to their logs - looking like a bug a in Gitea.
Now, there is no standard way in SQL to say Insert but if there's
an error ignore it. MySQL has INSERT IGNORE, PostgreSQL >= 9.5 has
INSERT ... ON CONFLICT DO NOTHING, but I do not believe that SQLite
or MSSQL have variants.
This PR places the insert in a transaction which we are happy to fail
if there is an error - hopefully this will stop the unnecessary
logging.
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>