Using IDE as git merge tool annoying due to Non project files protection

I setup Rider as my general git merge tool (following the steps here https://www.jetbrains.com/help/idea/command-line-merge-tool.html) and it seems to work fine.
However if I have a Rider session open in the background, and try to use it as a merge tool for files that are not part of the project (e.g. files from an entirely different git repo) I get prompted for “Non-Project Files Protection”.



This seems very out of place here, since I am running `rider merge …` on the command line. There is no reason to assume that command is related to some other Rider session that currently happens to be open. 

I think the “Non-Project Files Protection” should be disabled when starting rider from the command line, or at least when starting with the `diff`, `merge`, `format`, or `inspect` option.