This is probably a temporary build problem, but I thought mentioning
here might get it fixed faster in case it hasn't already been noticed.
https://download.postgresql.org/pub/repos/yum/testing/10/fedora/fedora-25-x86_64/
should have rpms but doesn't. I am using test rpms I got from there about
a week ago, but wanted to switch to the prebuilt beta version.