only emit a single space between mac length and the orginal id if the mac length is zero

(cherry picked from commit ac1c3aaa)
14 jobs for 540-tsig-has-two-consecutive-spaces-when-maclen-is-0-v9_11 in 7 minutes and 58 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #59244
amd64 docker linux

00:00:18

 
  Build
passed build:centos:centos6:amd64 #59245
amd64 docker linux

00:02:14

passed build:centos:centos7:amd64 #59246
amd64 docker linux

00:02:23

passed build:debian:sid:amd64 #59247
amd64 docker linux

00:01:27

passed build:debian:sid:i386 #59248
i386 docker linux

00:01:45

 
  Test
passed install:debian:sid:amd64 #59257
amd64 docker linux

00:01:57

passed systemtest:centos:centos6:amd64 #59253
amd64 docker linux

00:04:45

passed systemtest:centos:centos7:amd64 #59254
amd64 docker linux

00:04:56

passed systemtest:debian:sid:amd64 #59255
amd64 docker linux

00:04:57

passed systemtest:debian:sid:i386 #59256
linux i386 docker

00:05:13

passed unittest:centos:centos6:amd64 #59249
amd64 docker linux

00:01:14

passed unittest:centos:centos7:amd64 #59250
amd64 docker linux

00:01:12

passed unittest:debian:sid:amd64 #59251
amd64 docker linux

00:01:03

passed unittest:debian:sid:i386 #59252
i386 docker linux

00:01:06