Description of problem:
Illegal CL input results in NULL csr when requesting external ca.

[root@ipa ~]# ipa-server-install --external-ca --external_cert_file=/root/ipa.crt --external_ca_file=/etc/pki/tls/certs/Foo-CA.crt 

The log file for this installation can be found in /var/log/ipaserver-install.log
==============================================================================
This program will set up the FreeIPA Server.

This includes:
  * Configure the Network Time Daemon (ntpd)
  * Create and configure an instance of Directory Server
  * Create and configure a Kerberos Key Distribution Center (KDC)
  * Configure Apache (httpd)

To accept the default shown in brackets, press the Enter key.

Enter the fully qualified domain name of the computer
on which you're setting up server software. Using the form
<hostname>.<domainname>
Example: master.example.com.


Server host name [ipa.foo.com]: 

The domain name has been calculated based on the host name.

Please confirm the domain name [foo.com]: 

The IPA Master Server will be configured with
Hostname:    ipa.foo.com
IP address:  192.168.0.1
Domain name: foo.com

The kerberos protocol requires a Realm name to be defined.
This is typically the domain name converted to uppercase.

Please provide a realm name [FOO.COM]: 
Certain directory server operations require an administrative user.
This user is referred to as the Directory Manager and has full access
to the Directory for system management tasks and will be added to the
instance of directory server created for IPA.
The password must be at least 8 characters long.

Directory Manager password: 
Password (confirm): 

The IPA server requires an administrative user, named 'admin'.
This user is a regular system account used for IPA server administration.

IPA admin password: 
Password (confirm): 
Password mismatch!

IPA admin password: 
Password (confirm): 


The following operations may take some minutes to complete.
Please wait until the prompt is returned.

Configuring certificate server: Estimated time 6 minutes
  [1/4]: creating certificate server user
  [2/4]: creating pki-ca instance
  [3/4]: restarting certificate server
  [4/4]: configuring certificate server instance
The next step is to get /root/ipa.csr signed by your CA and re-run ipa-server-install as:
ipa-server-install --external_cert_file=/path/to/signed_certificate --external_ca_file=/path/to/external_ca_certificate
[root@ipa ~]# cat ipa.csr
null


Version-Release number of selected component (if applicable):
ipa-server-2.0.0-23.el6.x86_64



Additional info:
I know it is an illegal construction using the command line, but it either ought ot be prevented or well it probably ought to be prevented.