While trying to use Seas0npass (0.7.8) to create IPSW, I had same failure as reported by some other users - patch filesystem failed with reason blah blah. After studying log file, I found one line saying “/bin/sh: chown command not found”. This reminded me to check my environment vars ( I set them in ~/.MacOSX/environment.plist), and that’s it. I mis-spelled /usr/sbin which is just where chown lies in. I corrected it and restarted and run Seas0npass, and it worked well.
So I suggest other users who had the same problems take a look at log file to check if they set PATH correctly. echo $PATH to check if /usr/sbin is set.
Hope this could be some help.