Change call to Split() to safer SplitN()
Change call to Split() to safer SplitN()

Change calls to Split to SplitN when we are splitting on an "=" sign to make sure
we're not over chopping what the caller requested.

I started this search after seeing https://github.com/containers/podman/pull/7759.
I'll do similar for Podman, but initial results on my search is order of
magnitudes bigger there.

Signed-off-by: TomSweeneyRedHat <0d9c75ecdfb440d0db7595b9f1ea08841c99bb0e@redhat.com>

nalind/buildah-1,rhatdan/buildah,projectatomic/buildah,TomSweeneyRedHat/buildah,TomSweeneyRedHat/buildah,nalind/buildah-1,nalind/buildah-1,rhatdan/buildah,rhatdan/buildah,nalind/buildah,projectatomic/buildah,projectatomic/buildah,TomSweeneyRedHat/buildah,nalind/buildah