How does the plugin repository handle multiple plugin versions?

Use case:
A plugin stops working with the latest version (build 666).
=> the author fixes it, and publishes the new version with the appropriate
"since-build=666"
info.

Question:
Is it enough for an author to publish the new version, or
does he also have to patch the previous version, by adding
"until-build=665" in the plugin.xml?

Alain