Red Hat Certificate System web based configuration "Internal Server Error" and RA "Could not find httpd.xml" in DisplayCertChainPanel.pm

Issue

Adding a sub system to a subordinate CA may fail in some environments.
The Red Hat Certificate System web based configuration of subsystem may fail with the following generic error in the browser:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, you@example.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
"

And in the case of a RA configuration failure in a specific PKI topology with a root CA, a subordinate CA and one "security domain", in the RA logs:

==> /var/log/pki-ra2/debug <==
...snip...
Tue Dec 2 06:52:33 PST 2014 - RA wizard: uri='/ra/admin/console/config/wizard'
Tue Dec 2 06:52:33 PST 2014 - RA wizard: http parameter name='p' value='2'
Tue Dec 2 06:52:33 PST 2014 - RA wizard: http parameter name='op' value='next'
...snip...
Tue Dec 2 06:52:33 PST 2014 - DisplayCertChainPanel: update

==> /var/log/pki-ra2/error_log <==
[Tue Dec 02 06:52:33 2014] [info] Connection to child 20 established (server ca1.example.com:19890, client 10.14.5.177)
[Tue Dec 02 06:52:33 2014] [info] Initial (No.1) HTTPS request received for child 20 (server ca1.example.com:19890)
GET /ca/admin/ca/getDomainXML HTTP/1.0
...snip...
[Tue Dec 02 06:52:33 2014] [error] [client 10.14.5.177] Could not find httpd.xml in /usr/sbin/ at /var/lib/pki-ra2/lib/perl/PKI/RA/DisplayCertChainPanel.pm line 228\n, referer: https://ca1.example.com:19890/ra/admin/console/config/wizard
~~~