1.0.5 regression: tarball tasks run tar with incorrect options (namely, none)

[SethTisue]

after we upgraded https://github.com/scala/scala-dist from sbt-native-packager 1.0.4 to 1.0.6, the universal-docs:packageXzTarball and universal-docs:packageZipTarball tasks stopped working correctly, e.g. at https://scala-ci.typesafe.com/job/scala-2.11.x-release-package-unix/356/console where we see:

java.lang.RuntimeException: Error tarballing /home/jenkins/workspace/scala-2.11.x-release-package-unix/target/universal-docs/scala-docs-2.11.8-f6bd712-nightly.txz. Exit code: 2

by ssh'ing in to the CI server and running the tasks manually I was able to get more informative error logs:

> universal-docs:packageXzTarball,
...
Running with tar /tmp/sbt_7bbb8416/scala-docs-2.11.7.tar scala-2.11.7
tar: Old option 'b' requires an argument.
Try 'tar --help' or 'tar --usage' for more information.
[trace] Stack trace suppressed: run last universal-docs:packageXzTarball for the full output.
[error] (universal-docs:packageXzTarball) Error tarballing /home/jenkins/workspace/scala-2.11.x-release-package-unix/target/universal-docs/scala-docs-2.11.7.txz. Exit code: 2
> universal-docs:packageZipTarball
Running with tar /tmp/sbt_1205a627/scala-docs-2.11.7.tar scala-2.11.7
tar: invalid option -- '/'
Try 'tar --help' or 'tar --usage' for more information.
[trace] Stack trace suppressed: run last universal-docs:packageZipTarball for the full output.
[error] (universal-docs:packageZipTarball) Error tarballing /home/jenkins/workspace/scala-2.11.x-release-package-unix/target/universal-docs/scala-docs-2.11.7.tgz. Exit code: 64

I believe the culprit is #666. the Running with lines above are actually complete invocations of tar, they just don't look like it because there are no flags. but yeah, it really is running tar without any flags such as -pcvf.

as for why, well, this key is empty:

> universal-docs:packageXzTarball::universalArchiveOptions
[info] List()

because since #666, in the sources we see universalArchiveOptions in packageKey := Nil, should be Seq("-pcvf") IMO (or perhaps include --force-local too, I see in other PRs there's been back-and-forth on that that I had difficulty following)

there's a defaultUniversalArchiveOptions in the sources that has the right value, but for some reason it isn't taking effect.

in scala/scala-dist#159 I worked around the problem by adding these settings:

universalArchiveOptions in (UniversalDocs, packageZipTarball) := Seq("--force-local", "-pcvf")
universalArchiveOptions in (UniversalDocs, packageXzTarball) := Seq("--force-local", "-pcvf")

[muuki88]

Thanks for the detailed description @SethTisue
We forgot to add the default options for docs packaging. Will fix this on the WE.