On master (f3a91ab0edc70e1bcb7e770f0878f03459c399e1) the build log for ARM contains:
$ export FILE_ENV="./ci/test/00_setup_env_arm.sh"
$ export QEMU_USER_CMD=""
$ export Can=
$ export run=
$ export the=
$ export tests=
$ export natively=
$ export without=
$ export qemu=
Setting up build cache
...
and

With this PR:
$ export FILE_ENV="./ci/test/00_setup_env_arm.sh"
$ export QEMU_USER_CMD=""
Setting up build cache
...
and

Also Travis build config validation added:
