overlay_dirs with tar layers is broken

[tych0]

tych0@e57508f fails

/cc @peusebiu

[tych0]

not ok 1 overlay_dirs works
# (in test file test/overlay-dirs.bats, line 33)
#   `umoci unpack --image oci:first dest' failed
# stacker version v0.18.0-1-ge57508f
# No uid mappings, running as root
# stacker version v0.18.0-1-ge57508f
# no previous storage type detected
# using storage backend overlay
# initializing stacker recipe: stacker.yaml
# substituting $STACKER_ROOTFS_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots
# substituting $STACKER_STACKER_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/.stacker
# substituting $STACKER_OCI_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/oci
# stacker build order:
# 0 build /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/stacker.yaml: requires: []
# building: 0 /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/stacker.yaml
# substituting $STACKER_ROOTFS_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots
# substituting $STACKER_STACKER_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/.stacker
# substituting $STACKER_OCI_DIR to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/oci
# Dependency Order [first]
# preparing image first...
# loading oci:/home/tycho/packages/stacker/test/centos:latest
# unpacking to /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots/first
# lxc rootfs overlay arg overlayfs:/home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots/sha256_cf1be318c6989edd4ac5076094a70c1015212ac7e5c2c4a33c9581da913d720a/overlay:/home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots/sha256_a1d0c75327776413fa0db9ed3adcdbadedc95a662eb1d360dad82bb913f8a1d1/overlay:/home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots/first/overlay
# stacker version v0.18.0-1-ge57508f
# stacker subcommand: [/home/tycho/packages/stacker/stacker --oci-dir /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/oci --roots-dir /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/roots --stacker-dir /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/.stacker --storage-type overlay --internal-userns --debug internal-go check-aa-profile lxc-container-default-cgns]
# bind mounting /home/tycho/packages/stacker/stackertest-test_overlay-2d5fdirs_works.I7agOC/.stacker/imports/first into container
# + '[' -f /file1 ']'
# + '[' -f /file2 ']'
# + '[' -x /executable ']'
# Generating overlay_dirs layers
# setting git version annotation to v0.18.0-1-ge57508f
# filesystem first built successfully
#    ⨯ create runtime bundle: unpack rootfs: create gzip reader: gzip: invalid header

[eusebiu-constantin-petu-dbk]

Hey Tycho, tried to reproduce this but failed to do it.
I added these lines:

    umoci unpack --image oci:first dest
    [ -f dest/rootfs/file1 ]
    [ -f dest/rootfs/file2 ]
    [ -x dest/rootfs/executable ]

running tests in modes: priv
1..5
ok 1 overlay_dirs works
ok 2 import from overlay_dir works
ok 3 overlay_dirs dest works
ok 4 overlay_dirs cache works
ok 5 overlay_dirs don't preserve ownership
running tests in modes: unpriv
1..5
ok 1 overlay_dirs works
ok 2 import from overlay_dir works
ok 3 overlay_dirs dest works
ok 4 overlay_dirs cache works
ok 5 overlay_dirs don't preserve ownership

[eusebiu-constantin-petu-dbk]

look #287