Puppetserver ignores custom reports

I am trying to write a custom report but the code doesn't seem to be picked up by the Puppetserver (2.2.0). Following https://puppetlabs.com/blog/when-puppet-reports-part-2 I have written a small module with a dummy report that only writes out a single line to the server log. The module is available at https://github.com/smoeding/puppet-foobar

First environment: Puppet 3.6.2, Debian Wheezy

• Install module foobar
• Verify parameters in puppet.conf: pluginsync=true, reports=foobar
• Start the puppetmaster
• Run puppet agent -t
• Observe the creation of /var/lib/puppet/lib/puppet/reports/foobar.rb

The logfile shows a successful call to the report (last line):

Info: Caching node for xxx

Info: Caching node for xxx

Notice: Compiled catalog for xxx in environment production in 9.54 seconds

Info: Puppet run on xxx ended with status unchanged

So the report code seems to be working in this environment.

Second Environment: Puppetserver 2.2.0, Puppet-Agent 1.3.0, Debian Wheezy

• Install module foobar
• Verify parameters in puppet.conf: pluginsync=true, reports=foobar
• Start the puppetmaster
• Run puppet agent -t
• Observe creation of /opt/puppetlabs/puppet/cache/lib/puppet/reports/foobar.rb

The logfile /var/log/puppetlabs/puppetserver/puppetserver.log only contains:

2015-11-25 18:49:12,105 WARN  [qtp559733227-62] [puppet-server] Puppet No report named 'foobar'

So the report is configured but obviously not registed in the server. Restarting the Puppetserver does not change that situation and the warning remains.

When I manually copy the file foobar.rb to
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/reports (where the standard report files http.rb, log.rb and store.rb reside), then the report suddenly works:

2015-11-25 19:04:14,042 INFO  [qtp1605533662-61] [puppet-server] Puppet Puppet run on yyy ended with status unchanged

It seems to me as if the documented way of writing a custom report as part of a module does not cause the new Puppetserver to pick up the deployed code and execute the report. Other code in modules (custom facts, types & providers) works the expected way.