Previously it read legacy facts, which are deprecated and slowly going away. It drops all the various hacks that were needed for older versions on the assumption they're no longer needed.
Facter 2.4 introduced the structured os fact while Facter 3.0 added the os.hardware fact to it. rspec-puppet-facts relies on those, so Facter versions older than 3.0 are no longer supported.
It also drops workarounds for Facter < 3.4 on Windows.
Previously it read legacy facts, which are deprecated and slowly going away. It drops all the various hacks that were needed for older versions on the assumption they're no longer needed.
Facter 2.4 introduced the structured os fact while Facter 3.0 added the os.hardware fact to it. rspec-puppet-facts relies on those, so Facter versions older than 3.0 are no longer supported.
It also drops workarounds for Facter < 3.4 on Windows.