It displays the reason for the "invalid" case.
Before:
1 2015-05-19 13:34:16.720640 (invalid)
After:
1 2015-05-19 13:34:16.720640 [cookie length 10 > 8] (invalid)
This is a follow-up to 8c7221d39b.
Add the poc test file from GitHub issue #783 (first packet).
Moreover:
Remove some extra blank lines.