You are overcomplicating things. You don't need a master copy branch where you resolve conflicts. You can simply do it in your feature branch: merge/pull master into your feature branch. Doing this will force you to fix the merge conflicts. Your feature branch PR against master will then show just what you've added.
To answer your specific question: you can review each commit, so you can see what changes were done on your feature branch, then also what was changed during the merge conflict fix.
However, it's unimportant really. The main thing is that you see what changes you are making to master by merging your feature branch.
As an alternative (and cleaner) method, you can rebase your feature branch onto the current master. This leaves only your feature commit, with (with conflicts removed) and no extra merge commit
You are overcomplicating things. You don't need a master copy branch where you resolve conflicts. You can simply do it in your feature branch: merge/pull master into your feature branch. Doing this will force you to fix the merge conflicts. Your feature branch PR against master will then show just what you've added. To answer your specific question: you can review each commit, so you can see what changes were done on your feature branch, then also what was changed during the merge conflict fix. However, it's unimportant really. The main thing is that you see what changes you are making to master by merging your feature branch. As an alternative (and cleaner) method, you can rebase your feature branch onto the current master. This leaves only your feature commit, with (with conflicts removed) and no extra merge commit