findpgpkey: dont die if Return-Path is missing

findpgpkey.py

@@ -266,6 +266,8 @@ if __name__ == '__main__':
         eml = parser.parse(sys.stdin.buffer)
 
         for key in ['From', 'Return-Path']:
+            if key not in eml:
+                continue
             variants = create_variants(eml[key])
             addresses.append(variants)