Possibly fix "maintainer-shell-script-fails-syntax-check" message

Cause is cryptic, but could be due to the shebang:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=478192
7 jobs for fix/ancient-standards in 2 minutes and 8 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #4155
build-deb:buster

00:01:30

passed #4153
build-deb:jessie

00:01:25

passed #4154
build-deb:stretch

00:01:46

 
  Test
failed #4158
test-deb:buster

00:00:19

failed #4156
test-deb:jessie

00:00:21

failed #4157
test-deb:stretch

00:00:21

 
  Deploy
skipped #4159
aptly
 
Name Stage Failure
failed
test-deb:stretch Test
No job log
failed
test-deb:buster Test
No job log
failed
test-deb:jessie Test
No job log