Merge commit 'b85c387c5c0527b0ad31c27031a09d361826c5fc' into glitch-soc/merge-upstream

Conflicts:
- `config/initializers/content_security_policy.rb`:
  Kept our version, it was not affected by upstream's bug.

app/models/account.rb

@@ -62,9 +62,9 @@ class Account < ApplicationRecord
     trust_level
   )
 
-  USERNAME_RE   = /[a-z0-9_]+([a-z0-9_\.-]+[a-z0-9_]+)?/i
-  MENTION_RE    = /(?<=^|[^\/[:word:]])@((#{USERNAME_RE})(?:@[[:word:]\.\-]+[[:word:]]+)?)/i
-  URL_PREFIX_RE = /\Ahttp(s?):\/\/[^\/]+/
+  USERNAME_RE   = /[a-z0-9_]+([a-z0-9_.-]+[a-z0-9_]+)?/i
+  MENTION_RE    = %r{(?<=^|[^/[:word:]])@((#{USERNAME_RE})(?:@[[:word:].-]+[[:word:]]+)?)}i
+  URL_PREFIX_RE = %r{\Ahttp(s?)://[^/]+}
   USERNAME_ONLY_RE = /\A#{USERNAME_RE}\z/i
 
   include Attachmentable