Bug: when changing the user handle, the as_dict field is not updated in the profile

When changing the user handle, the as_dict field is not updated in the profile:

This causes for example side effects with the bounties:
- when users express interest, this is registered to their old handle not the new one (even though the login shows the new handle)

No file, test, or entry point is named. Reproduce the problem by changing a user's handle, then trace where the profile's as_dict value is assembled and consumed by bounty interest records. Done means the profile reflects the new handle and newly recorded interests no longer retain the old one; add or update a regression test if the existing test structure identifies a suitable location.

Written by the indexing model from the issue text.