cqlengine: fix map remove feature for non-nullable values#1241

dkropachev wants to merge 1 commit intodatastax:masterdatastax/python-driver:masterfrom

dkropachev:dk/dx-cqlengine-map-remove-for-non-nullable-valuesdkropachev/python-driver:dk/dx-cqlengine-map-remove-for-non-nullable-valuesCopy head branch name to clipboard