From: rsbecker@nexbridge.com <redacted> 

I am not convinced this is a defect. The result of --shortstat is to
report that there are differences, so it is possible that 0 is correct
here. Others might have a different opinion. I can recreate without
including any other options.

The code has already done the work to identify if there are differences. Why would it not return a meaningful exit code?
This e-mail, including attachments, may include confidential and/or
proprietary information, and may be used only by the person or entity
to which it is addressed. If the reader of this e-mail is not the intended
recipient or intended recipient’s authorized agent, the reader is hereby
notified that any dissemination, distribution or copying of this e-mail is
prohibited. If you have received this e-mail in error, please notify the
sender by replying to this message and delete this e-mail immediately.