Extracting **all** the pre-merged code associated with a PR, not just the diffs?

[Hippo Potamus]

Is there a way to extract all the code from a given PR, before the code has been approved and merged?

What we'd like to do is get the current state of each and every file associated with the PR, not just the diffs associated with the PR itself.

In other words, we'd like to do something which will extract the all the existing files as well as all the newer files that comprise the diffs in this PR, so that we will be able to get a snapshot of what the code base would look like after a merge from the PR is done.

The reason we want to do this is because we suspect that someone might have accidentally messed up the PR or something else related to our repo so that the "master" branch that the PR thinks that it's based upon is not actually our real master branch. We'd like to do this extract that I'm describing and then manually diff it against the full code base from the actual master branch, to see whether something like this might have occurred.

Is there any way to do this?

Thank you very much in advance for any thoughts and suggestions.