Memcache issue on staging/testing overwrites newer data with old when any edit happens

### Evidence / Screenshot (if possible)

### Relevant url?
https://openlibrary.org/works/OL1914022W/The_Pillars_of_the_Earth?m=history
See v28/29

### Steps to Reproduce

1. Edit a work record on prod.
2. Go to http://staging.openlibrary.org/works/merge?records=OL...W,OL...W
3. Confirm merge.
4. See that last edit is reverted.

* Actual: Edits on production are lost.
* Expected: Merge tool is supposed to fetch the work data from production.

### Details

- **Logged in (Y/N)?** Y
- **Browser type/version?**
- **Operating system?**
- **Environment (prod/dev/local)?** prod and staging

### Proposal & Constraints

### Related files

### Stakeholders

@cdrini @seabelis