One of the issues that Github presents is that any pull request lists not only the commits included, but all of the commits that the developer has contributed. This makes it hard to identify how far back to test code. A quick solution is to include the the hash key of the first commit in the current pull request. You can easily obtain this hash from the Github Desktop looking at the history. Click on the commit on the column at the left, them click on the hash key at the top of the screen to copy it to the clipboard.
It is also helpful to include the list of commits in the notes of the pull request:
Debug: Logout Script; Redirect Header changed to 303.
Feature: System File Management.
Render: Remove Finder and sidebar when screen width decreases.
CSS: Hamburger Menu Colour and position changes.
Feature: Page Anchor Display Switch