build.sh: check if gluon got modified and bail out if necessary

build.sh

@@ -114,7 +114,8 @@ pushd ${CODE_DIR} > /dev/null
 
 ### CHECKOUT GLUON
 progress "Checking out GLUON '${BASE}' ..."
-# TODO: check if gluon got modified and bail out if necessary
+# check if gluon got modified and bail out if necessary
+[ "$(git status --porcelain)" ] && abort "Local changes to peers directory. Cowardly refusing to update gluon repository." >&2
 git fetch
 git checkout -q ${BASE}
 [ "$?" -eq "0" ] || abort "Failed to checkout '${BASE}' gluon base version, mimimi." >&2