Building custom Nerves system in Docker with external directory exposed

nerves_docker_build.txt

Making install in checks
make[5]: Nothing to be done for 'install-exec-am'.
make[5]: Nothing to be done for 'install-data-am'.
Making install in tests
/usr/bin/make  install-recursive
Making install in .
make[7]: Nothing to be done for 'install-exec-am'.
make[7]: Nothing to be done for 'install-data-am'.
libtool-2.4.6.tar.xz: OK (sha256: 7c87a8c2c8c0fc9cd5019e402bed4292462d00a718a7cd5f11218153bf28b26f)
>>> host-libtool 2.4.6 Extracting
/tmp/rpi2_out/host/usr/bin/xzcat /nerves_system_br/buildroot-2016.08/dl/libtool-2.4.6.tar.xz | tar --strip-components=1 -C /tmp/rpi2_out/build/host-libtool-2.4.6   -xf -
tar: bootstrap: Cannot change ownership to uid 501, gid 50: Permission denied
tar: m4/ltversion.m4: Cannot change ownership to uid 501, gid 50: Permission denied
tar: libltdl/Makefile.am: Cannot change ownership to uid 501, gid 50: Permission denied
tar: build-aux/ltmain.sh: Cannot change ownership to uid 501, gid 50: Permission denied
tar: Exiting with failure status due to previous errors
package/pkg-generic.mk:134: recipe for target '/tmp/rpi2_out/build/host-libtool-2.4.6/.stamp_extracted' failed
make[1]: *** [/tmp/rpi2_out/build/host-libtool-2.4.6/.stamp_extracted] Error 2
Makefile:16: recipe for target '_all' failed
make: *** [_all] Error 2
root@011d07395a31:/tmp/rpi2_out#