If the content language is English and the message is invalid as
a username, or the content language is not English and both the
content language version and the English version are invalid, the
user in FilterUser would not be created - now, avoid the onwiki
version of the English message in the fallback, so it could only
be invalid if the default in the i18n files was invalid.
Bug: T284364
Change-Id: I9e9f44b7663e810de70fb9ac7f6760f83dd4895b
Unfortunately, this isn't using DI completely, because of the
User::newSystemUser call. I'm not even sure if we really need to call it
or we can just stick to new UserIdentityValue, but leaving like this for
now.
Also, the types were weakened to UserIdentity, so the transition is
going to be easy anyway.
Change-Id: I08f8fae0fcc622ff0ac3f86771476d06d1c18549
