Just a remark about the preamble comment: it reads to me as though PEP499 is a misfeature. Possibly change:

  We actually want the double import, so remove the alias if it exists.

to:

  This module is unusual, and actually wants the double import.
  Therefore we remove the __spec__.name alias if it exists
  so that a subsequent import by name will make a distinct instance.

Verbose, but at least I know the intent.