Correctly output the $FORCE_BUILD=true message in custom-docker-build
requested to merge memborsky/gitlab-build-images:correctly-output-FORCE_BUILD-equals-true into master
When attempting to build a custom-docker-build with $FORCE_BUILD=true, the notification message is attempting to shell execute the $FORCE_BUILD=true part of the string. This just dumps the $FORCE_BUILD=true message to the prompt instead of trying to execute 'true=true'.