JMeterThread.runPostProcessors() runs Post-Processors in reverse order - no idea why. This needs to be documented. The behaviour should be fixed, but to maintain backwards compatibility, this should depend on a JMeter property, so previous behaviour can be restored. [JMeter should log which behaviour is in force.]
Fixed in SVN
SVN r488856
This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/1837