Ok i am guessing that this was related to this change here d1199c225f1c66bd8365d10bee734f8330d84f20.
Since the default is ON, you must have the `xsltproc`, `lynx`, and `docbook2x-man`. I will improve the handling of this if it's the case Can you verify you do?
An alternative would set to the `-DBUILD_DOC=OFF` and it will behave as before.
On your successful RPM packaging, where the docs and man pages generated by calling explicitly the targets?