Git submodules in OpenZFS

From: Ed Maste <emaste_at_freebsd.org>
Date: Mon, 14 Jun 2021 15:38:58 UTC 
On Tue, 8 Jun 2021 at 10:53, Martin Matuska <mm@freebsd.org> wrote:
>
> The branch main has been updated by mm:
>
> URL: https://cgit.FreeBSD.org/src/commit/?id=1603881667360c015f6685131f2f25474fa67a72
>
> commit 1603881667360c015f6685131f2f25474fa67a72
> Merge: ed9215c8e05f 75b4cbf62590
> Author:     Martin Matuska <mm@FreeBSD.org>
> AuthorDate: 2021-06-08 14:48:37 +0000
> Commit:     Martin Matuska <mm@FreeBSD.org>
> CommitDate: 2021-06-08 14:52:44 +0000
>
>     zfs: merge openzfs/zfs@75b4cbf62 (master) into main

It turns out this has the side-effect of introducing submodule use, in
sys/contrib/openzfs/scripts/zfs-images. We can mostly ignore this for
FreeBSD, but it can introduce an issue for downstream projects that
intend to use submodules for some portion of their tree.

I encountered this because I have a WIP tree that incorporates pkg and
drm-kmod via submodules, and updating it produced the error:

fatal: No url found for submodule path
'sys/contrib/openzfs/scripts/zfs-images' in .gitmodules

There are a few different ways I think we could address this. Assuming
we don't need to use zfs-images in FreeBSD I believe the easiest will
be to just delete the directory/submodule in FreeBSD, e.g. `git rm
sys/contrib/openzfs/scripts/zfs-images`.