fix None comparison

16 jobs for master in 5 minutes and 17 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #42640
Linux
build-2.7-linux

00:01:23

passed #42641
Apple
build-2.7-macos

00:02:14

passed #42638
Linux
build-3.5-linux

00:01:25

passed #42639
Apple
build-3.5-macos

00:02:15

passed #42637
VS2017
build-3.6-VS2017

00:01:36

 
  Test
passed #42645
Linux
test-2.7-linux

00:00:08

passed #42646
Apple
test-2.7-macos

00:00:11

passed #42643
Linux
test-3.5-linux

00:00:05

passed #42644
Apple
test-3.5-macos

00:00:12

passed #42642
VS2017
test-3.6-VS2017

00:00:17

 
  Deploy
passed #42650
Linux
deploy-2.7-linux

00:00:01

passed #42651
Apple
deploy-2.7-macos

00:00:01

passed #42648
Linux
deploy-3.5-linux

00:00:01

passed #42649
Apple
deploy-3.5-macos

00:00:01

passed #42647
VS2017
deploy-3.6-VS2017

00:00:02

passed #42652
Linux
deploy-documentation

00:00:18