Why space is preserved in comma separated lists?

[anatoly techtonik]

If I do this:

  tasks:
  - name: install dependencies for screenshots under i3
    apt:
      package: maim, xclip

Ansible fails:

  fatal: [localhost]: FAILED! => {"changed": false, "msg": "No package matching ' xclip' is available"}

If space is removed, it works. Why not to strip space from lists automatically?