Diff table files not selectable

Items in the file diff table below certain row cannot be selected. This is true for both clicking and for pressing Cmd+A.

Consistently reproducible across different machines and repositories. Also, confirmed to have started recently with 4.2.6.

Easy steps to reproduce with an open source repository:

1. Using Sourcetree, clone Apple's [Device Management Client Schema|https://github.com/apple/device-management] repository.
2. Make sure that the latest `release` commit (`1cb86e0`) is selected.
3. Make sure that the file diffs table is set to a flat list (any of the two).
4. Press Cmd+A - only part of the items become selected.
5. Click on any of the rows that did not get selected in step 4 - nothing happens.