Revision user incorrectly appears as anonymous user when node author is cancelled

Problem/Motivation

The revision user is not appearing correctly on the /revisions tab when a node author is cancelled and their content assigned to anonymous user.

Steps to reproduce:

1. User A creates a node
2. User B edits that node
3. User C cancels User A's account and assigns their content to the anonymous user (user_cancel_reassign).
4. Go to the Revisions tab created in Step 1: the user for both revisions is Anonymous, where User B is expected for the second revision.

Proposed resolution

node_mass_update with both the uid and the revision_uid set to 0 is called for user_cancel_reassign. Not sure if this is the "root cause" and additional code is needed there instead of the simple assignment.

Remaining tasks

User interface changes

API changes

Data model changes