[root@nightly ~]# ll /etc/dhcp -d
drwxr-xr-x. 3 root root 4096 Oct 22 08:02 /etc/dhcp

[root@nightly ~]# yum reinstall dhcp
...
Complete!

[root@nightly ~]# ll /etc/dhcp -d 
drwxr-x---. 3 root root 4096 Oct 24 05:16 /etc/dhcp 

[root@nightly ~]# service foreman-proxy restart
Stopping foreman-proxy:                                    [  OK  ]
Starting foreman-proxy:                                    [  OK  ]

[root@nightly ~]# curl -H "Accept:application/json" -k --cert /var/lib/puppet/ssl/certs/nightly.zzz.lan.pem --key /var/lib/puppet/ssl/private_keys/nightly.zzz.lan.pem https://nightly.zzz.lan:8443/dhcp/192.168.222.0
Unable to find the DHCP configuration or lease files

[root@nightly ~]# chmod o+x /etc/dhcp

[root@nightly ~]# curl -H "Accept:application/json" -k --cert /var/lib/puppet/ssl/certs/nightly.zzz.lan.pem --key /var/lib/puppet/ssl/private_keys/nightly.zzz.lan.pem https://nightly.zzz.lan:8443/dhcp/192.168.222.0
{"leases":[],"reservations":[]}

Therefore the workaround is to do chmod o+x /etc/dhcp in the sysvinit/systemd startup script of the proxy.

QA: To verify the bug, use the scenario above, plus make sure the foreman installer in dry run (-n) does not print any other planned changes:

[root@nightly ~]# foreman-installer -v -n
...
[ WARN 2014-10-24 06:07:35 verbose]  /File[/etc/dhcp]/mode: current_value 0751, should be 0755 (noop)
...

Also try to reinstall other software to verify similar scenarios: dhcp, bind, tftp, puppet, bmc/ipmi, facter.