libreadline.so.6 => /lib/x86_64-linux-gnu/libreadline.so.6 (0x00007ff182e5d000)
libreadline is GPL'ed, not LGPLed, Kerf is therefore in violation.https://cnswww.cns.cwru.edu/php/chet/readline/rltop.html
Edit: The GPL doesn't allow any linking into non-GPL compatible software, dynamic or static. Readline has this license for exactly this reason, and they have forced software into the public with it before (ncftp comes to mind)
http://www.gnu.org/licenses/gpl-faq.en.html#GPLStaticVsDynam...
Edit2: https://en.wikipedia.org/wiki/GNU_Readline#Implications_of_G...