fpausp
Your yum-repository information is long out of date - version 8 hasn't been a "testing" release for a very long time.
I noticed on sme 8 servers upgraded from earlier versions (ie sme 7 or sme 8 betas), that repos could no longer be correct, including custom added repos. This issue did not exist to the same extent on the previous major version release (ie sme 6 to sme 7 upgrades), as yum was not around then or only in it's infancy. sme 7 has been around since 2007 IIRC, so many "newer" users would not have experienced a prior major version upgrade & be less knowledgable of some of the pitfalls of upgrading.
IMO when upgrading to a new major version, it's best to manually wipe out all repos using the commands to initialize default databases, thus resetting them to defaults (refer FAQ for details of commands), & then re-add any custom repos you require.
All repos will then have correct values (eg source locations) applicable to the current sme version installed (eg sme 8 ).