Deleting an LDAP user causes watchlist to hang

If a LDAP user is watching an existing ticket AND has a custom avatar, removing this user will cause the watchlist to hang.

Tested on JIRA: 5.1.6, 5.1.8, 5.2.2

Steps to reproduce:

• Setup JIRA + LDAP, doing a full sync
• Login as a LDAP user and add an avatar to their profile
• Watch an issue
• Delete this user from ldap
• Sync JIRA
• As another user, try to check the watchlist
  • Specifically, clicking the (#) number next to Watch (under Assignee)
• Note that JIRA just tries to load to no avail

Screenshots for more info

Workaround

• Right click the (#) and open in a new tab
  OR
• Click on More Actions > Watchers