You can always make changes and then not commit them. Changes will float when you pull / merge / lock / check; if you try to do something that overwrites them (for example, you merge a change concerning the same file), it will refuse - from that moment you can git stash to make changes, perform the operation, and then git stash (apply|pop) to restore the changes.
If you want these changes to be made locally, but not transferred to anyone else, I believe that your best choice is to support them in the local branch where you are rebuilding (or maintaining the merger) the industry "actual development" and just be careful not to actually push commit (s) that contain local changes.
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