My apologies but I don't have an unmodified copy of /etc/vsftpd.conf from Ubuntu 14.04 handy for comparison. Perhaps this will help.
If you have
chroot_list_enable activated, you may provide a list of local users who are placed in a chroot() jail in their home directory upon login.
The meaning is slightly different if chroot_local_user is set to YES. In this case, the list becomes a list of users which are NOT to be placed in a chroot() jail. By default, the file containing this list is /etc/vsftpd.chroot_list, but you may override this with the
chroot_list_file setting, Excerpt from man page for that seting is below.
The option is the name of a file containing a list of local users which will be placed in a chroot() jail in their home directory. This option is only relevant if the option
chroot_list_enable is enabled. If the option
chroot_local_user is enabled, then the list file becomes a list of users to NOT place in a chroot() jail.