Description of problem:
This one has failed a few times in the past couple of days with gccgo:
https://jenkins.dockerproject.org/job/Docker%20Master%20%28gccgo%29/1285/consoleFull
https://jenkins.dockerproject.org/job/Docker%20Master%20%28gccgo%29/1287/consoleFull
https://jenkins.dockerproject.org/job/Docker%20Master%20%28gccgo%29/1294/consoleFull

docker version:
1.10.10-dev (latest upstream)

docker info:
❗ This is to make Gordon happy, and should be ignored since it's from my laptop (running in a container), not one of Docker's test nodes.

./docker info

Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 0
Server Version: 1.10.0-dev
Storage Driver: devicemapper
Pool Name: docker-253:2-5914896-pool
Pool Blocksize: 65.54 kB
Base Device Size: 10.74 GB
Backing Filesystem: xfs
Data file: /dev/loop2
Metadata file: /dev/loop3
Data Space Used: 11.8 MB
Data Space Total: 107.4 GB
Data Space Available: 84.95 GB
Metadata Space Used: 581.6 kB
Metadata Space Total: 2.147 GB
Metadata Space Available: 2.147 GB
Udev Sync Supported: false
Deferred Removal Enabled: false
Deferred Deletion Enabled: false
Deferred Deleted Device Count: 0
Data loop file: /var/lib/docker/devicemapper/devicemapper/data
WARNING: Usage of loopback devices is strongly discouraged for production use. Either use --storage-opt dm.thinpooldev or use --storage-opt dm.no_warn_on_loop_devices=true to suppress this warning.
Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
Library Version: 1.02.82 (2013-10-04)
Execution Driver: native-0.2
Logging Driver: json-file
Plugins:
Volume: local
Network: null host bridge
Kernel Version: 4.2.8-200.fc22.x86_64
Operating System: Ubuntu 14.04.3 LTS (containerized)
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 7.678 GiB
Name: 703f7cbf4c89
ID: 5VYE:UHVY:NVE7:FXOH:6XFB:MT4G:2WOX:BXUT:5E7S:VFRS:EL4S:6HOX
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

uname -a:
❗ same comment as above.
4.2.8-200.fc22.x86_64

Environment details (AWS, VirtualBox, physical, etc.):
docker's jenkins (see above links)

How reproducible:
flaky. always seen by me in docker's jenkins builds

Steps to Reproduce:

1. someone commits something
2. it gets merged
3. the jenkins build is triggered

Actual Results:
Test always passes

Expected Results:
Sometimes it doesn't

Additional info:
I'll try to look into it today. I haven't tried recreating it locally but wanted to get it into an issue so others can "me too" it and so I don't forget about it.