ssh forced commands broken in current? (ssh_packet_send_debug: unknown error)

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Hi,

I got an alert that backups weren't running. It looks like forced
commands no longer work on the server side. Anyone else see this?

OpenSSH_6.8 NetBSD_Secure_Shell-20150403, OpenSSL 1.0.1m 19 Mar 2015
MKLLVM=yes

Test case in ~/.ssh/authorized_keys:

command="/usr/bin/uname -a",no-port-forwarding,no-X11-forwarding,no-pty
ssh-rsa AAAA...

Results in:

$ ssh -T tnn@localhost "/usr/bin/uname -a"
Connection to localhost closed by remote host.

# /usr/sbin/sshd -d
...
Accepted publickey for tnn from ::1 port 64821 ssh2: RSA SHA256:...
debug1: monitor_child_preauth: tnn has been authenticated by privileged process
debug1: mac 0x7f7ff7b2f9b0, 1 1 [preauth]
debug1: monitor_read_log: child log fd closed
debug1: PAM: establishing credentials
User child is on pid 12298
debug1: PAM: establishing credentials
debug1: ssh_packet_set_postauth: called
debug1: mac 0x7f7ff7b2f2b0, 1 1
debug1: mac 0x7f7ff7b2f2b0, 1 1
ssh_packet_send_debug: unknown error 1048
debug1: do_cleanup
debug1: do_cleanup
debug1: PAM: cleanup
debug1: PAM: closing session