Comment 8 for bug 972834

The port is defined as 0 by default. Modifying tftpd.c to initialize it as 69 and rebuilding the deb works:

$ diff tftpd.c tftpd-orig.c
68c68
< short tftpd_port = 69; /* Port atftpd listen to */
---
> short tftpd_port = 0; /* Port atftpd listen to */

You can still override it with --port on the command line. Not sure if this is the cleanest way to fix this.