Don't allow duplicates in the bugs field.
It's been possible for a long time to put in the same bug number twice. In the

past, this caused all sorts of nonsense (making it impossible to remove just

one of them), but with the fields rewrite the situation is much improved,

just being ugly.
I've added a filter to get_bug_list() which uses set() to de-dupe the list.

Theoretically it's still possible that a duplicate gets saved in the draft, but

it will never be shown to the user, and it will get filtered out when saving

the draft.

Tried to save the "Bugs" field with the same bug listed multiple times. Saw

that all my duplicates were filtered out.