Mark builds from git explicitly

Changed files
+1 -1
nixos
modules
installer
+1 -1
nixos/modules/installer/tools/get-version-suffix
···
if nixpkgs=$(nix-instantiate --find-file nixpkgs "$@"); then
getVersion $nixpkgs
if [ -n "$rev" ]; then
-
echo "pre-$rev"
+
echo ".git.$rev"
fi
fi