the following changes have been pushed to bugzilla.mozilla.org:

• [1021218] merge-users.pl fails if both users have bug_user_last_visit entries for the same bug
• [1017648] migrate mentors from the whiteboard to the mentor field
• [1026421] “No QA contact” represented by “” instead of null
• [1026415] Some empty fields are present as “” rather than being absent
• [1026862] updating a bug via an api or bulk bug update clears the mentor field
• [1026400] id, attachment.id, attachment.bug_id are returned as strings, not integers