When usernames are updated in an external user directory (e.g. LDAP or Crowd), @username mentions in pull request comments are not updated in Bitbucket.

Steps to replicate

• @ mention a user in a pull request comment (for example: "@user1")
• change the username in the external directory (e.g. change "user1" to "user2")
• sync the user directory to Bitbucket
• the @username mention in the pull request comment is not updated (e.g. it still shows "@user1")

Other areas of the application are updated with the new username (username shown in Commits page, permissions settings, pull request reviewers, account settings).