In case anyone sees this thread: this wasn't connected to gem.coop, it was entirely a problem of having multiple source lines, which is a feature that is deprecated and in fact entirely removed at the head of rubygems/rubygems

Looks like rubygems.org gave me libv8 (7.3.492.27.1-universal-darwin-16), however gem.coop gave me libv8 (7.3.492.27.1-universal-darwin16), missing the final "-", but told me it was the former.

Is there a place (or account) that I can/should direct questions about things like this to?

libv8 (7.3.492.27.1-universal-darwin-16) sha256=5ef3cd13ac6b4bc0451aaaf951b21f159549a0670c2230bdd8393af4a259c822
from the API at rubygems.org
libv8 (7.3.492.27.1-universal-darwin-16) sha256=79893222ab1ffa2914e4b06f7bb486112bc8db8e6276074d6b984806470a605d
from the API at gem.coop

I think this is a really good thing, and I'm very excited by it; however, on attempting to use it, I discovered that some gems have differing sha256 when compared to rubygems.org, for example libv8, specifically 7.3.492.27.1-universal-darwin-16.