Only enable github-rspec for pull requests

Do not merge, just a test

.github/workflows/test-ruby.yml

@@ -113,7 +113,7 @@ jobs:
       CAS_ENABLED: true
       BUNDLE_WITH: 'pam_authentication test'
       CI_JOBS: ${{ matrix.ci_job }}/4
-      GITHUB_RSPEC: ${{ matrix.ruby-version == '.ruby-version' }}
+      GITHUB_RSPEC: ${{ matrix.ruby-version == '.ruby-version' && github.event.pull_request && 'true' }}
 
     strategy:
       fail-fast: false

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