inscrutable TLS server engine error log message

[Patrick Goetz]

Whenever I run; e.g.

   imtest -t "" mail.spinningwheel.org

(or basically any TLS connection) the following error is logged:

TLS server engine: No CA file specified. Client side certs may not work

I first noticed this on a couple of 2.3.16 installs, but now the same 
thing is happening in 2.4.17.  Everything was working on the 2.3.16 
systems, so I didn't bother with it, but this time around I'm trying to 
track down every possible configuration issue.

Note that it doesn't seem to make any difference how I set up the TLS 
configuration in imapd.conf, this error message persists.

Is there any way to make this go away, or is this one of the things that 
will get magically fixed in 2.5?