fix: permit selecting a different tar filter for artifacts

[stuart-warren]

permit working with ubuntu core

ref: canonical#165

add extra flag -tar-filter to select alternative to xz which is not available in core base snaps

[maykathm]

This is great; thanks for making this change. I tested it out, and it's really useful to be able to get artifacts from core. I would love to see this merged.

[zyga]

I ran into exactly this limitation and I'd love to be more pragmatic here. Perhaps we can just revert to gz and pursue the option separately, so that default just works?

[stuart-warren]

I would be happy with the default changing back also

[stuart-warren]

@zyga is that a change you would like me to make? I believe @niemeyer made the original change to xz.

[jocado]

Hi @zyga

I also have an interest in getting this merged.

How best to make progress on this. Do you know if it needs anyone particularity to review it, or how we can progress it ?

Thanks!

[zyga]

@jocado I don't have any ability to merge this. Please reach out to @cmatsuoka perhaps.

[zyga]

@stuart-warren I think it's important to have a default that just works so yeah. I know about the original choice.

[stuart-warren]

@zyga I created #234

[stuart-warren]

No longer needed