Description of problem:
The system.listBaseChannels api method is supposed to "Return a list of
subscribable base channels." What it actually returns is apparently a list of:
1) the current base channel
2) custom channels that you can subscribe to as the base channel
It should return all subscribable base channels so you can set a new one with
the setBaseChannel method. 

Version-Release number of selected component (if applicable):
5.0.6

How reproducible:
Always

Steps to Reproduce:
1. set base channel for server (in this example auto_test_2, 1012737455) to a
Red Hat channel, for example RHEL 4 AS
2. run attached script against server 
3. change base channel to a custom channel, for example GRGRHEL5Parent
4. run attached script again
  
Actual results:
The first time it will list RHEL 4 AS and GRGRHEL5Parent.
The second time it will only list GRGRHEL5Parent

Expected results:
Both times it should list all available base channels; the same as what you see
in the drop-down.

Additional info: