Description of problem:
ipa-server must depend on a version of httpd that support mod_proxy with UDS, as a result noticed that ipa-server upgrade failed for upgrade path 7.0 > 7.3.

Version-Release number of selected component (if applicable):
ipa-server-4.4.0-8.el7.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Setup IPA server on RHEL 7.0 (in my case ipa-server-3.3.3-28.el7.x86_64)
2. Use the latest repo links for RHEL 7.3
3. Now update the ipa server with command "yum -y update 'ipa*' sssd"

Actual results:
1. IPA-server upgrade fails.
2. After upgrade:
#  journalctl -l -u httpd.service
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test systemd[1]: Starting The Apache HTTP Server...
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test ipa-httpd-kdcproxy[13706]: ipa         : INFO     KDC proxy enabled
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test httpd[13707]: AH00526: Syntax error on line 113 of /etc/httpd/conf.d/ipa.conf:
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test httpd[13707]: ProxyPass URL must be absolute!
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
Aug 24 03:08:06 auto-hv-01-guest09.testrelm.test systemd[1]: Failed to start The Apache HTTP Server.
line 113 is:  ProxyPass "unix:/run/httpd/ipa-custodia.sock|http://localhost/keys/"

3. # rpm -q httpd
httpd-2.4.6-17.el7.x86_64

4. # tail -f /var/log/ipaupgrade.log
    self.service.start(instance_name, capture_output=capture_output, wait=wait)
  File "/usr/lib/python2.7/site-packages/ipaplatform/base/services.py", line 285, in start
    skip_output=not capture_output)
  File "/usr/lib/python2.7/site-packages/ipapython/ipautil.py", line 489, in run
    raise CalledProcessError(p.returncode, arg_string, str(output))

2016-08-24T07:08:06Z DEBUG The ipa-server-upgrade command failed, exception: CalledProcessError: Command '/bin/systemctl start httpd.service' returned non-zero exit status 1
2016-08-24T07:08:06Z ERROR Unexpected error - see /var/log/ipaupgrade.log for details:
CalledProcessError: Command '/bin/systemctl start httpd.service' returned non-zero exit status 1
2016-08-24T07:08:06Z ERROR The ipa-server-upgrade command failed. See /var/log/ipaupgrade.log for more information

5.# ipactl status
Directory Service: STOPPED
Directory Service must be running in order to obtain status of other services
ipa: INFO: The ipactl command was successful
[root@auto-hv-01-guest09 log]# ipactl restart
Starting Directory Service
Starting krb5kdc Service
Starting kadmin Service
Starting named Service
Failed to start named Service
Shutting down
Hint: You can use --ignore-service-failure option for forced start in case that a non-critical service failed
Aborting ipactl
[root@auto-hv-01-guest09 log]# kinit admin
kinit: Generic error (see e-text) while getting initial credentials
[root@auto-hv-01-guest09 log]# ipactl start
Existing service file detected!
Assuming stale, cleaning and proceeding
Starting Directory Service
Starting krb5kdc Service
Starting kadmin Service
Starting named Service
Failed to start named Service
Shutting down
Hint: You can use --ignore-service-failure option for forced start in case that a non-critical service failed
Aborting ipactl
 


Expected results:
Ipa-server upgrade should be successful and no errors should be observed.

Additional info:
The upgrade was successful for 7.1 > 7.3