Broken systemd_process_cpu_seconds_total metric in 0.6.0

[amarao]

Version 0.6.0 is no longer reporting systemd_process_cpu_seconds_total metric. It reported it in version 0.5.0.

Example:

# ./systemd_exporter-0.5.0.linux-amd64/systemd_exporter &
# curl http://localhost:9558/metrics|grep cpu|wc -l
29
kill %1

Version 0.6.0 is not reporting:

./systemd_exporter-0.6.0.linux-amd64/systemd_exporter &
curl http://localhost:9558/metrics|grep cpu|wc -l
0
kill %1