corteca exec sequence prints null instead of command output

[kapcom01]

corteca-cli build: cfaf921
corteca.yaml: https://github.com/kapcom01/corteca-mlab-app/blob/c30bef9589fe088e5606fab094fd8a9b8210fc3c/corteca.yaml

$ corteca exec install qemu
root@127.0.0.1:2222's password:
Selected device 'qemu', protocol: ssh
Executing sequence 'install'
null
null
null
null
null
null
null
Sequence completed successfully!