Putative fix to crash in IPv4 DHCP, introduced whilst
generalising the DHCP option filter code:
don't match options against context tag  when
context->netid.net == NULL, since there's no tag then.
diff --git a/src/dhcp-common.c b/src/dhcp-common.c
index 2e40447..6de8e61 100644
--- a/src/dhcp-common.c
+++ b/src/dhcp-common.c
@@ -102,7 +102,7 @@
     }
 
   /* now flag options which are valid, including the context tags,
-     otherwise valid options are inhibited if we found a higher priotity one above */
+     otherwise valid options are inhibited if we found a higher priority one above */
   if (context_tags)
     {
       struct dhcp_netid *last_tag;