When rebuilding, the new build has the "Started by user" populated with the value from the source build, not the details of the user who requested the rebuild.

I.e.:

1. User Alice triggers Build 1 
2. Build 1 completes and states "Started by user Alice".
3. User Bob opens Build 1 and clicks "Rebuild", triggering Build 2.
4. Build 2 completes and states "Started by user Alice" but should have stated "Started by user Bob".

This creates confusion for accountability and auditing.

Reverting to Rebuilder plugin 1.29 fixes the issue.

Two other users have also reported the issue here on the PR for the release which introduced the bug:

https://github.com/jenkinsci/rebuild-plugin/pull/56#issuecomment-478868354