propelorm/Propel — pull request #436 by Martiusweb (2012-08-03 12:54:41+00:00)
Title: Abstract static method replaced by a runtime exception in *Peer

According to strict PHP standards with PHP 5.2 and more, abstract static
functions are not allowed.

This post on Stack Overflow summarize main points about this topic:
http://stackoverflow.com/questions/999066/why-does-php-5-2-disallow-abstract-static-class-methods