With a framework version that is not a release (a devel build, an empty
FrameworkVersion) every plugin with a minimum was marked as needing a
newer framework, and Compatible looked only at the newest release, so a
plugin whose older release fits was marked although plugin:install
would install that release. An unknown framework now gives no marker
(and no needs-framework note on the Installed tab), and a plugin whose
newest release is too new is looked up (cached, four at a time) and
counts as compatible when an older release fits.