[BUG] unable to edit action graph annotation about code HOT 1 CLOSED

Occurring due to a combination of some factors

• The way "existing" relations are checked
• SQL unique index constraint on token graph table, disallowing multiple relations between same two tokens,
• Soft delete

Current check uses a combination of (src_id, label_id, dst_id), so when (s0, l0, d0) exists and we try to remove that and add (s0, l1, d0), first will be marked for deletion, yet be there with is_deleted = True, and we check if (s0, l1, d0) exists, and upon finding out it doesn't, we try to add it. => Unique relation label for (s0, d0) violated.

Solution: Use (src_id, dst_id) to check for "existing" relations, and update label_id to the submitted one.

from code.