Fix where() in delete_invalid_entries
Fix where() in delete_invalid_entries

`== None` should be used in the filter, not `is None`.

HamutalCohen3/anyway,HamutalCohen3/anyway,OmerSchechter/anyway,esegal/anyway,omerxx/anyway,boazin/anyway,hasadna/anyway,idogi/anyway,HamutalCohen3/anyway,idogi/anyway,yosinv/anyway,idogi/anyway,hasadna/anyway,yosinv/anyway,esegal/anyway,esegal/anyway,OmerSchechter/anyway,hasadna/anyway,hasadna/anyway,omerxx/anyway,boazin/anyway,omerxx/anyway,boazin/anyway,OmerSchechter/anyway,yosinv/anyway