Never rpm post exit with retval > 0

I was updating a dysfunctional test VM and got this:
```
Non-fatal POSTIN scriptlet failure in rpm package nagios-okconfig-nrpe-0.0.5-1.el6.noarch
nrpe dead but subsys locked
warning: %post(nagios-okconfig-nrpe-0.0.5-1.el6.noarch) scriptlet failed, exit status 2
```
This change should hide the message from ```service status``` and never exit with higher values than 0