Windows: do not let isGitOnPath() look at the current working directory
Windows: do not let isGitOnPath() look at the current working directory

On Windows, `where.exe` has this feature where it looks in the current working directory first. But we do not want to pick up a `git.exe` from the current directory (nor a `git.cmd`, which `where git` would _also_ find).

Let's just execute the `where git` command in Windows' system directory, where it is pretty much guaranteed that no `git.exe` exists.

shiftkey/desktop,artivilla/desktop,shiftkey/desktop,artivilla/desktop,j-f1/forked-desktop,desktop/desktop,j-f1/forked-desktop,say25/desktop,kactus-io/kactus,kactus-io/kactus,desktop/desktop,kactus-io/kactus,say25/desktop,j-f1/forked-desktop,desktop/desktop,say25/desktop,kactus-io/kactus,j-f1/forked-desktop,shiftkey/desktop,artivilla/desktop,desktop/desktop,say25/desktop,shiftkey/desktop,artivilla/desktop