Ignore ENOENT when modifying route metrics.

kernel.c

@@ -597,7 +597,7 @@ kernel_route(int operation, const unsigned char *dest, unsigned short plen,
         if(rc < 0 && errno != EEXIST)
             return rc;
         rc = kernel_route(ROUTE_FLUSH, dest, plen, gate, ifindex, metric, 0);
-        if(rc < 0 && errno == ESRCH)
+        if(rc < 0 && (errno == ENOENT || errno == ESRCH))
             rc = 1;
         return rc;
     }