bash fdesc requirement?

[Gary Aitken]

Building up a 9.3-release system.
After doing a pkg upgrade I see this message:

Message for bash-4.3.30_1:
 ======================================================================
bash requires fdescfs(5) mounted on /dev/fd
If you have not done it yet, please do the following:
        mount -t fdescfs fdesc /dev/fd
To make it permanent, you need the following lines in /etc/fstab:
        fdesc   /dev/fd         fdescfs         rw      0       0

Yet it seems to run just fine without it.  (simple test, start bash and
exit...)

Can someone explain what's going on, and why one would or would not 
add the indicated line to /etc/fstab?

Thanks,

Gary