Description of problem:
Remote command ending with '&' do not fork out from rhn_check process. Command is running successfilly but it doesn't return the promt to parrent process. So, rhn_check still waiting the end of execution, like as '&' is absent.

Steps to Reproduce:
1. create remote command ending with '&' (for running in background)
2. run rhn_check on client machine
3.
  
Actual results:

Summary: 	Run an arbitrary script scheduled by spaceadmin
Details: 	This action will be executed after 03/22/13 9:41:00 AM MSK.

This action's status is: Failed.
The client picked up this action on 03/22/13 9:43:55 AM MSK.
The client completed this action on 03/22/13 9:45:59 AM MSK.
Client execution returned "Script killed, timeout of 120 seconds exceeded" (code 1)


Run as: root:root
Timeout: 120 seconds

#!/bin/sh
(tail -f /var/log/somelogfile > /tmp/dest_file) &


Start Date: 2013-03-22 00:00:00
End Date: 2013-03-22 00:00:00
Return Code: 0
Raw Output: view/download raw script output
Filtered Output:


Expected results:
rhn_check shouldn't wait the end of execution of remote command running in background (like as it happens with manual command execution in bash)

Additional info:
# rhn_check -vvv
<...>
D: do_call script.run(45, {'username': 'root', 'groupname': 'root', 'now': '2013-03-22 10:43:55', 'timeout': 120, 'script': '#!/bin/sh\n(tail -f /var/log/somelogfile > /tmp/dest_file) &'}){'cache_only': None}
D: Sending back response(1, 'Script killed, timeout of 120 seconds exceeded', {'output': '', 'base64enc': 1, 'process_end': '2013-03-22 10:45:57', 'return_code': 0, 'process_start': '2013-03-22 10:43:55'})
D: do_call packages.checkNeedUpdate('rhnsd=1',){}
<...>