Older versions of Mesos have issues with newlines in app labels

[JayH5]

In certain versions of Mesos prior to 1.2.1/1.3.0, a bug in Mesos (MESOS-6951) causes problems with app labels that contain new lines when Marathon also provides those app labels as environment variables. This issue would cause the marathon-acme container to fail to start.

An ugly workaround is to force Marathon to not store the app label as an environment variable by making the label longer than 512 bytes:

"HAPROXY_0_HTTP_FRONTEND_ACL_WITH_PATH": "  acl path_{backend} path_beg {path}\n  use_backend {backend} if path_{backend}\n  ##################################################################\n  # This is a terrible hack to make the value of the marathon app\n  # label containing this config snippet longer than 512 bytes,\n  # which is the threshold beyond which marathon doesn't try to turn\n  # it into an environment variable.\n  # See https://issues.apache.org/jira/browse/MESOS-6951 for an\n  # explanation of why this is necessary.\n  ##################################################################\n",