(PUP-3024) Add deltarpm_percentage and deltarpm_metadata_percentage

This patch adds deltarpm_percentage and deltarpm_metadata_percentage to the yumrepo type.
These yum repo configuration options are only available with newer versions of Fedora and CentOS 7, which have DeltaRPM support (Presto).

Earlier versions of yum appear to ignore options which aren't recognised, loading the repo file successfully.

- Does there need to be added logic which rejects this parameter for earlier OS versions? (This could be quite a bit of work and other modules such as the puppetlabs-apt one are not doing something similar currently)

- Should I also create some kind of (doc) tracking ticket for this as well?


After a brief look around I found this:
https://cedarandthistle.wordpress.com/2013/05/31/eulogy-for-yum-presto/ which gives the history of deltarpms in Fedora. It seems that before Fedora 19, this was available through a plugin called presto (package: yum-presto). After this point, deltarpm functionality was built into yum itself. So perhaps check if Fedora 19 first, then check if the yum presto plugin is loaded by checking for /etc/yum/pluginconf.d/presto.conf for [main] enabled = 1 since earlier versions of the Redhat family could have had this plugin enabled as well.

I am not a Fedora or Ruby expert by any means, but will take a look at the PR you linked to see if I can contruct a feature check.