"tar: This does not look like a tar archive" when piping from git archive about buildstep HOT 14 OPEN

libcontainer|master ⇒ git archive HEAD |  docker run -i ubuntu:14.04 /bin/bash -c "mkdir -p /app && tar -xC /app"
libcontainer|master ⇒ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
libcontainer|master ⇒ docker ps -a
CONTAINER ID        IMAGE               COMMAND                CREATED             STATUS                      PORTS               NAMES
b71dbf644fd7        ubuntu:14.04        "/bin/bash -c 'mkdir   7 seconds ago       Exited (0) 6 seconds ago                        evil_ptolemy
d34e448971fb        ubuntu:14.04        "/bin/bash -c 'mkdir   17 seconds ago      Exited (2) 16 seconds ago                       kickass_hopper
16900e8ca046        ubuntu:14.04        "bash -c 'echo start   2 minutes ago       Exited (0) 2 minutes ago                        focused_euclid
07b69fbab6c2        ubuntu:14.04        "bash -c 'echo start   2 minutes ago       Exited (0) 2 minutes ago                        cranky_nobel
libcontainer|master ⇒ docker commit b71dbf644fd7
cbbb86058a73308e95a58edcc99d01258cea6c8c5fc5f5cdea8a48230194611a
libcontainer|master ⇒ docker run -ti cbbb86058a73308e95a58edcc99d01258cea6c8c5fc5f5cdea8a48230194611a bash
root@3233cab43416:/# ls
app  bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
root@3233cab43416:/# cd app
root@3233cab43416:/app# ls
CONTRIBUTORS_GUIDE.md  NOTICE         apparmor        container.go  namespaces  sample_configs  system
Dockerfile             PRINCIPLES.md  cgroups         devices       netlink     security        types.go
LICENSE                README.md      config.go       factory.go    network     selinux         utils
MAINTAINERS            ROADMAP.md     config_test.go  label         nsinit      state.go
MAINTAINERS_GUIDE.md   api_temp.go    console         mount         process.go  syncpipe
root@3233cab43416:/app# exit
exit
libcontainer|master ⇒