fix ansible warning

3 jobs for bind9_without_collectd in 47 seconds (queued for 2 minutes and 13 seconds)
Status Job ID Name Coverage
  Build
failed #297
build

00:00:47

 
  Test
skipped #299
allowed to fail
code_quality
skipped #298
test
 
Name Stage Failure
failed
build Build

Skipping Git submodules setup
$ [[ "$TRACE" ]] && set -x # collapsed multi-line command
$ if [[ -z "$CI_COMMIT_TAG" ]]; then # collapsed multi-line command
$ /build/build.sh
Building Heroku-based application using gliderlabs/herokuish docker image...
invalid argument "/bind9-without-collectd:a6f1e665e54ef7ebd70a0447fdafe52face170fd" for "-t, --tag" flag: invalid reference format
See 'docker build --help'.
ERROR: Job failed: exit code 1