Eu descobri que há um bug no nano < 2.7.4-1
nano: / etc / nanorc é ignorado, se ~ / .nanorc existir
Latest from the bug report:
I just made the dist-upgrade to Debian 9.0, which included an update of package nano to version 2.7.4-1 and the problem vanished, the bug is solved in 2.7.4-1.
O relatório de erros: bug