[Bug 1218599] New: docker can no longer copy from inside the container

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1218599

Bug ID: 1218599
           Summary: docker can no longer copy from inside the container
           Product: Fedora
           Version: 21
         Component: docker-io
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail], [e-mail],
                    [e-mail]

Created attachment 1022155
  --> https://bugzilla.redhat.com/attachment.cgi?id=1022155&action=edit
dockerfile reproducer

Description of problem:
After upgrading docker I can no longer cp from inside a container. I upgraded
to docker-io-1.6.0-4.git350a636.fc21.x86_64 and tried
docker-io-1.6.0-4.git350a636.fc21.x86_64 as well. Both fail.

This is a regression in F21. That worked fine with 1.3.2

How reproducible:
Outside the container use:
docker cp my_container:/tmp/file-created-in-the-container ./tmp/
FATA[0000] Error response from daemon: Could not find the file ...

Using ssh I can verify that the files exist

Steps to Reproduce:
0. Copy the attached dockerfile into docker-dir
1. sudo docker build -t test-image docker-dir
2. sudo docker run -P --privileged=true --name xxx-name test-image
3. sudo docker cp xxx-name:/tmp/xxx /tmp/

Actual results:
With 1.3.2: nothing. The file is copied.

With 1.6.0:
FATA[0000] Error response from daemon: Could not find the file /tmp/xxx in
container xxx-name

Expected results:
The file should have been copied.