vendormoduledir not configurable

Puppet Version: 6.26.0
Puppet Server Version: 6.19.0
OS Name/Version: Solaris 11.4 (agent), RHEL7 (server)

Solaris uses /usr/puppetlabs as location where Linux uses /opt/puppetlabs.

Although there is a configuration directive called vendormoduledir it is never read from settings.

Desired Behavior:

The configuration command vendormoduledir can be customized to point to /usr/puppetlabs/puppet/vendor_modules for instance.

Actual Behavior:

The path for vendor_modules is hardcoded and can't be changed. This causes that custom iinstalled modules can not be found and the catalog can not be applied if resources are being used like:

Puppet (err): Failed to apply catalog: Resource type 'Ssh_authorized_key' was not found

Workaround:

Create a symbolic link from /usr/puppetlabs to /opt/puppetlabs.