Avatar/information missing when file gets edited via public link

[juliusknorr]

Steps to reproduce

1. Share a file via a public link and make it editable
2. Let an anonymous user edit the file (e.g. via collabora online)
3. Browse File change activity

Expected behaviour

Maybe show "Someone has changed $file"

Actual behaviour

Missing avatar is shown

[nickvergessen]

Already fixed on master, backport is awaiting review:
nextcloud/server#5063

Feel free to +1 it