Rows of Vertical Down Piston Extenders have a >50% failure rate

When pistons are lined up in a row, facing downward (useful for portcullis) more then half of the second set of pistons fire out of order and it creates a graphical glitch as well. When the block next to the piston is powered it is more likely to power the piston below it then the piston next to it, this is counter intuitive and not how it acts in 1.4.7. This bug was reported several times for last snapshot but always got tagged as being a duplicate for another unrelated bug that is reported as fixed.