I have this strange behavior here: (chroot) vh ~ # qfile -v /etc/signon-ui/webkit-options.d/www.facebook.com.conf net-libs/signon-oauth2-0.21-r1 (/etc/signon-ui/webkit-options.d/www.facebook.com.conf) kde-apps/kaccounts-providers-16.12.3 (/etc/signon-ui/webkit-options.d/www.facebook.com.conf) qfile reports that the 'www.facebook.com.conf' file is installed by two packages at the same time...
what does grep -FH "/etc/signon-ui/webkit-options.d/www.facebook.com.conf" /var/db/pkg/{net-libs/signon-oauth2-0.21-r1,kde-apps/kaccounts-providers-16.12.3}/CONTENTS return?