add support for polling yum repos

[glensc]

this would help peeking into yum metadata file, like primary.xml.gz in this project:

https://release-monitoring.org/project/5513/

or maybe just add support for yum repository files?

[ralphbean]

This needs a new 'yum' backend to be implemented to handle looking into releases like that.

[yarons]

Are you sure it's a good practice because that means it was already packaged, in some cases this is the only source code but it would be just like polling packed code from PPA or Debian repository.

[Zlopez]

This project is not in packaged in any distribution, but only in some private repository. In this case the 'yum' (dnf) backend is not a bad idea.

[carlwgeorge]

I maintain a library that may be useful for whoever tries to implement this, whether as a dependency or just as example code of parsing yum repodata in python.

https://pypi.org/project/repomd/

[glensc]

@carlwgeorge so elegant code. awesome.

already using it: https://github.com/pld-linux/google-chrome/commit/fe67123c73f041f55b839fce96e30f461cb0caa7