jailer in 4.9

[Chris Jones]

The jailer command from ports (sysutils/jailer) is very useful for 
running stuff like webservers under user control.  Unfortunately, the 
version in ports doesn't seem to work with 4.9: I get an error claiming 
that jailer couldn't determine whether it was in a jail ("Could not 
determine jailed status.").

Has anyone been able to get jailer working under 4.9?  Did the jail 
system change between 4.8 and 4.9?

Cheers,

Chris