Add srpm source location

[ehelms]

This fills a gap in the srpm.py module that was added a few months back. A source location and source type can now be specified that will download sources into the buildroot. This mimcs the behavior that tito used to provide in this area and is focused on supporting our primary use of downloading nightly sources from Jenkins. This will require changes to the package manifest to support it:

    foreman:
      releasers:
        - "{{ nightly_releaser }}"
      build_package_tito_releaser_args: "{{ nightly_package_tito_releaser_args }}"
      nightly_package_tito_releaser_args:
        - "jenkins_job=foreman-develop-source-release"
        - "jenkins_url=https://ci.theforeman.org"
      build_package_tito_builder: "tito.builder.FetchBuilder"
      source_location: https://ci.theforeman.org/job/foreman-develop-source-release
      source_system: jenkins

Note the last two new parameters. I am not sold on the naming convention of the variables, so feel free to offer new ideas. The tito arguments will have to remain for a period of time as those are still used by the koji build functionality (#230 aims to close that gap).

This is built on top of #278 which touches the same file.

[evgeni]

@ehelms would you mind rebasing and fixing the " C: 59, 0: Missing function or method docstring (missing-function-docstring)" pylint error?

[evgeni]

comments on the python code, but happy with the overall "this is how it shall work in obal"

variable names are fine too

[ehelms]

To get python 2.7 I had to change my approach and dance around with urllib being different in Py2 and Py3.

[evgeni]

Ansible vendors six, and that has six.moves to take care of these games.

So you could do smth like:

from ansible.module_utils.six.moves.urllib.request import urlopen
from ansible.module_utils.six.moves.urllib.error import HTTPError

(untested)

But you don't have to, just a comment ;)

[evgeni]

I thought more of a global, static var (SOURCE_SYSTEM_URLS), but wouldn't mind either way here.

[ehelms]

I was worried about scope creep, and I figured if I went this route and there was a reason to go with a global static variable you'd point it out to me :)

[evgeni]

Ansible has open_url, fetch_url and fetch_file in https://github.com/ansible/ansible/blob/devel/lib/ansible/module_utils/urls.py which could be used instead, but I don't think we buy anything by using them here.

[evgeni]

left a few comments what could be done differently without really thinking it'd be better ;-)