/etc/ntp.d/ is not scanned if /etc/ntp.conf fails to be opened
From docs/includes/ntpd-body.adoc
Configuration files are parsed according to the following rules:
- The plain config file (normally {ntpconfpath} but the path can be overridden by the -c option) is read first if it exists.
- Then the configuration directory, if it exists, is scanned. Normally this directory is /etc/ntp.d, but if the -c option is specified the /etc will be specified by the directory name of the -c argument.
If the attempt to open /etc/ntp.conf fails, since commit bbb82f1f ntpd will exit without scanning the configuration directory.
This behavior would appear to be at odds with the documented configuration parsing rules.