+
+ (* In util-linux <= 2.19, mkswap -U cannot handle the first byte of
+ * the UUID being zero, so we artificially rewrite such UUIDs.
+ * http://article.gmane.org/gmane.linux.utilities.util-linux-ng/4273
+ *)
+ if s.[0] = '0' && s.[1] = '0' then
+ s.[0] <- '1';
+