hub/email: ignore cc/bcc empty strings. maybe related to #2507
hub/email: ignore cc/bcc empty strings. maybe related to #2507

sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc