dhcp: ensure any dhclient script from dhclient.conf is ignored

The config file can specify a dhclient script, which gets used instead
of what NM passes on the command-line.  Make sure that script gets
ignored in the final dhclient config, because the script NM passes
is the script that needs to be used to pass data back to NM.  People
may have old dhclient.conf files lying around that get picked up and
we don't want any script specified there to interfere.

src/dhcp-manager/nm-dhcp-dhclient-utils.c

@@ -168,6 +168,10 @@ nm_dhcp_dhclient_create_config (const char *interface,
 					continue;
 			}
 
+			/* Ignore 'script' since we pass our own */
+			if (g_str_has_prefix (p, "script "))
+				continue;
+
 			/* Check for "also require" */
 			if (!strncmp (p, ALSOREQ_TAG, strlen (ALSOREQ_TAG))) {
 				in_alsoreq = TRUE;