Each version of Pressflow is API-compatible with the same major Drupal version. For example, Pressflow 6 is compatible with all Drupal 6 modules. Pressflow 6 also integrates the SimpleTest system from Drupal 7 and the CDN support patch.
Fix broken Pressflow page cache lifetime due to use of non-existent config variable, and incorrectly treating it as a timestamp.
It looks like at some stage someone has tried to fix the default Drupal behaviour of caching pages with CACHE_TEMPORARY. However it has never worked because 1. the wrong variable name is used and 2. even if the correct variable name had been used, the variable stores a TTL but cache_set requires a timestamp.
Fix broken Pressflow page cache lifetime due to use of non-existent config variable, and incorrectly treating it as a timestamp.
It looks like at some stage someone has tried to fix the default Drupal behaviour of caching pages with CACHE_TEMPORARY. However it has never worked because 1. the wrong variable name is used and 2. even if the correct variable name had been used, the variable stores a TTL but cache_set requires a timestamp.
See https://github.com/pressflow/6/pull/33 (earlier incomplete pull request) https://www.drupal.org/node/1279654 https://www.drupal.org/node/2130865