MTR hangs on IPv6 UDP trace when both --localport and --port are specified.

[tyleeds]

MTR will hang when you attempt to do an IPv6 trace on UDP when both the local port and destination port are specified.

Works as expected if either local port OR destination port are specified, but not if both are.

Example:

 mtr -z -i.3 -b 2606:4700::1111 --udp --localport 50001 --port 50256

This does not appear to affect IPv4 or --tcp traces.

Confirmed on MTR 0.92 and 0.95