Can you try after setting the NSS_SSL_ENABLE_RENEGOTIATION environment variable to 1 ? (with nss 3.12.5-1, obviously).
Running iceweasel from a terminal using the following solved the issue for me:
NSS_SSL_ENABLE_RENEGOTIATION=1 iceweasel -- Oliver -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
