Merge branch 'da/user-useconfigonly' into HEAD

Merge branch 'da/user-useconfigonly' into HEAD

The "user.useConfigOnly" configuration variable makes it an error
if users do not explicitly set user.name and user.email.  However,
its check was not done early enough and allowed another error to
trigger, reporting that the default value we guessed from the
system setting was unusable.  This was a suboptimal end-user
experience as we want the users to set user.name/user.email without
relying on the auto-detection at all.

* da/user-useconfigonly:
  ident: give "please tell me" message upon useConfigOnly error
  ident: check for useConfigOnly before auto-detection of name/email