Docker crashes on HEAD

[Samuel Cassiba]

I've been playing around with Docker on FreeBSD and have encountered some
crashiness. When I go to jump in a container using 'docker exec', if I
accidentally typo the command, the Docker daemon itself crashes, which
leaves the host and any running containers in an inconsistent state. The
biggest standout from the logs seems to be:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x1b pc=0x8dadcb]

After the Docker daemon is restarted, I am unable to restart existing
containers, with Docker saying that the file system is busy.

The full output from docker.log after the Docker daemon crashes is at:
https://gist.github.com/scassiba/dfdb75361de42b41636c

The output from docker.log after attempting to restart the Docker daemon
and a container is at: https://gist.github.com/scassiba/abb821563b2e8cb742cc

Has anyone seen this on a recent copy of HEAD?

Thanks.