Printing from a default Fedora 23 install gives you raw jobs (application/octet-stream) to the client, rather than a proper PDF.
Found the problem and reported it upstream:
In short, printing a PDF means that no conversion is needed. In this case CUPS sets FINAL_CONTENT_TYPE incorrectly. The correct type is however in CONTENT_TYPE so we may be able to do a workaround.
This is aggravated by the fact that modern distributions have switched over to PDF as the internal format, rather than PostScript. This means that most print jobs will be PDF and hit this bug.
Tested using build 4970. Works as expected.