pgbouncer systemd does not work on CentOS 7

After installing pgbouncer-1.5.5-1.rhel7.x86_64.rpm on CentOS 7.0, it
does not remain running.  No errors are logged.

I think the systemd configuration is faulty.  It currently reads

[Service]
Type=forked

...

ExecStart=/usr/bin/pgbouncer -d -v ${BOUNCERCONF}

If I change that to

[Service]
Type=simple

...

ExecStart=/usr/bin/pgbouncer -v ${BOUNCERCONF}

it works

Alternatively, the first version can be made to work by adding
RemainAfterExit=yes.

But clearly, the second version is more in line with the systemd philosophy.