GitFileIsolator calls git checkout (and a few other git commands) with the full list of file paths in one command invocation. Theoretically if there are thousands of paths with hundreds of characters each, this could fail on some systems. `getconf ARG_MAX` is more than 2 million on my workstation, so potentially that would allow about 10,000 args with length 200 each... so this probably is probably not an issue, but it still might be on some other systems.

If this ever becomes an issue we might have to run the commands with the paths separated into batches.