“ Since the decision below, and after hearing reargument in the Opelika case, we have vacated our earlier judgment and held the license tax imposed in that case to be unconstitutional. Jones v. Opelika, 319 U.S. 103, 63 S.Ct. 890, 87 L.Ed. --; Murdock v. Pennsylvania, 319 U.S. 105, 63 S.Ct. 870, 87 L.Ed. --. Petitioners urge us to construe the District of Columbia statute as inapplicable in order to avoid the constitutional infirmity which might otherwise exist-an infirmity conceded by respondent on the oral argument before us. ”