Add check to abort if run under Windows (git will fail).
Add check to abort if run under Windows (git will fail).


Former-commit-id: cd4d3dd758ff83b0640173708005bdd27e5c21e4
bfg-repo-cleaner-demos/eclipselink.runtime-bfg-strip-big-blobs,bfg-repo-cleaner-demos/eclipselink.runtime-bfg-strip-big-blobs,bfg-repo-cleaner-demos/eclipselink.runtime-bfg-strip-big-blobs