Description of problem:


Version-Release number of selected component (if applicable):


How reproducible:
100%

Steps to Reproduce:
1. Install oracle db listening on <hostname> nic
2. Create /etc/tnsnames.ora and define an oracle service name
# vim /etc/tnsnames.ora 
the_oracle =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = <fqdn>)(PORT = 1522))
    )
    (CONNECT_DATA =
      (SID = xrhnsatx)
    )
  )

3. Run installer a provide db connect info either as service name or as db name + host + port
# ./install.pl --external-oracle
* Starting the Spacewalk installer.
* Performing pre-install checks.
* Pre-install checks complete.  Beginning installation.
* RHN Registration.
** Registration: System is already registered with RHN.  Not re-registering.
* Checking for uninstalled prerequisites.
* Installing RHN packages.
* Now running spacewalk-setup.
* Setting up Selinux..
* Setting up Oracle environment.
* Setting up database.
** Database: Setting up database connection for Oracle backend.
'' is not a valid response
Database hostname [localhost]? 
'' is not a valid response
Database (listener) port [1521]? 
*** Database connection error: ORA-12541: TNS:no listener (DBD ERROR: OCIServerAttach)
Database service name (SID)? the_oracle
*** Database connection error: ORA-01017: invalid username/password; logon denied (DBD ERROR: OCISessionBegin)
Username? spaceuser
Password? 
** Database: Testing database connection.
** Database: Populating database.

>>> though installer allows you to specify service name and credentials, still needlessly asks for a hostname and a port before  (not needed when using service name)


# ./install.pl --external-oracle
* Starting the Spacewalk installer.
* Performing pre-install checks.
* Pre-install checks complete.  Beginning installation.
* RHN Registration.
** Registration: System is already registered with RHN.  Not re-registering.
* Checking for uninstalled prerequisites.
* Installing RHN packages.
* Now running spacewalk-setup.
* Setting up Selinux..
* Setting up Oracle environment.
* Setting up database.
** Database: Setting up database connection for Oracle backend.
'' is not a valid response
Database hostname [localhost]? <fqdn>
'' is not a valid response
Database (listener) port [1521]? 1522
*** Database connection error: ORA-12514: TNS:listener does not currently know of service requested in connect descriptor (DBD ERROR: OCIServerAttach)
Database service name (SID)? xrhnsatx.world
Database hostname [localhost]? <fqdn>
Database (listener) port [1521]? 1522
*** Database connection error: ORA-01017: invalid username/password; logon denied (DBD ERROR: OCISessionBegin)
Username? spaceuser
Password? 
** Database: Testing database connection.
** Database: Populating database.

>>> when you specify db name, installer correctly asks also for hostname and port, resulting in user being asked twice for the same input. 

Actual results:
- too early and needlesly asking for hostname and port before the decisive input is provided by user (service name vs. db name)
- complaints "'' is not a valid response" are displayed
- errors from conection trials are displayed

Expected results:
- asks for service name or db name prior any other input about db connection details 
- no mess displayed


Additional info: