Ignore generic avatars from Slack

[auscompgeek]

Potentially terrible feature request, but here goes anyway.

Slack now has very unimaginative fallback user images - they all look like this, but with different colours:

I personally feel Riot's fallback avatar generation is more useful, but opinions may differ here. :man_shrugging:

This is a request to ignore the default avatars when fetching from Gravatar (i.e. iff the avatar URL is Gravatar, and we get the default, ignore it).

[Cadair]

Do you have examples of what we could use to detect the default? We would also want to be able to unset avatars if they changed to a default one.

[auscompgeek]

The only way I can think of is to check whether it's a Gravatar URL, and change the d query parameter (or remove it and check whether the hash of the returned image is the same as the Gravatar logo?).