IndexFile.remove: shell command length limit might be hit

[Byron]

On windows, there can be a command line length overflow as the shell might be used there to make the git command call as we pass the paths directly as argv. This is as we use git-rm to be able to remove whole directories easily.

Alternatively, the index could be manipulated in-python or using git-update-index, and the working tree adjustments would have to be hand implemented then which might be some work to get it right ( and well tested ).