Merge commit 'c676bc91e9c3aa81eb7cfbce3c5c5e80b84d3d02' into glitch-soc/merge-upstream

Conflicts:
- `config/environments/production.rb`:
  Upstream enforced a code style change and glitch-soc had a few different lines.
  Applied upstream's code style to glitch-soc's changes.

app/models/account.rb

@@ -66,7 +66,7 @@ class Account < ApplicationRecord
   BACKGROUND_REFRESH_INTERVAL = 1.week.freeze
 
   USERNAME_RE   = /[a-z0-9_]+([a-z0-9_.-]+[a-z0-9_]+)?/i
-  MENTION_RE    = %r{(?<=^|[^/[:word:]])@((#{USERNAME_RE})(?:@[[:word:].-]+[[:word:]]+)?)}i
+  MENTION_RE    = %r{(?<![=/[:word:]])@((#{USERNAME_RE})(?:@[[:word:].-]+[[:word:]]+)?)}i
   URL_PREFIX_RE = %r{\Ahttp(s?)://[^/]+}
   USERNAME_ONLY_RE = /\A#{USERNAME_RE}\z/i