Add back mega-sdist (fixes snoyberg/mega-sdist#4)
Add back mega-sdist (fixes snoyberg/mega-sdist#4)

creichert/stackage,simonmichael/stackage,michalkonecny/stackage,ethercrow/stackage,mstksg/stackage,clinty/stackage,wereHamster/stackage,jonschoning/stackage,soenkehahn/stackage,lwm/stackage,massysett/stackage,int-index/stackage,asr/stackage,iand675/stackage,spencerjanssen/stackage,Daniel-Diaz/stackage,mgajda/stackage,stackbuilders/stackage,phaazon/stackage,Shimuuar/stackage,garetxe/stackage,peti/stackage,fimad/stackage,mrkkrp/stackage,fpco/stackage,athanclark/stackage