Description of problem:
When install ipa-server or ipa replica, they replace on /etc/ntp.conf server configured previusly by hand/user to this server:

### Added by IPA Installer ###
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org
server 127.127.1.0
fudge 127.127.1.0 stratum 10

Version-Release number of selected component (if applicable):
[root@ipaserver ~]# rpm -qa | grep ipa
ipa-python-3.0.0-37.el6.x86_64
ipa-pki-common-theme-9.0.3-7.el6.noarch
ipa-admintools-3.0.0-37.el6.x86_64
libipa_hbac-1.9.2-129.el6.x86_64
ipa-server-3.0.0-37.el6.x86_64
ipa-pki-ca-theme-9.0.3-7.el6.noarch
ipa-server-selinux-3.0.0-37.el6.x86_64
libipa_hbac-python-1.9.2-129.el6.x86_64
python-iniparse-0.3.1-2.1.el6.noarch
ipa-client-3.0.0-37.el6.x86_64
[root@ipaserver ~]#

How reproducible:
Always

Steps to Reproduce:
1. configure ntp.conf to point to your closest ntp server (intranet or internet server)
2. install ipa server or ipa replica


Actual results:
ipa server replace ntp server on ntp.conf

Expected results:
no change anymore ntp server