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

Decide on alternative in case there are large number of revisions.

User interface changes

API changes

Data model changes