Formaline: only create new build id if something changed
Formaline: only check for GNU tar once
this makes consecutive "make" calls no-ops (once more)
This addresses https://bitbucket.org/einsteintoolkit/tickets/issues/1223/formaline-always-triggeres-new-link
Formaline: only check for GNU tar once
Formaline: only create new build id if something changed
this makes consecutive "make" calls no-ops (once more)
This addresses https://bitbucket.org/einsteintoolkit/tickets/issues/1223/formaline-always-triggeres-new-link