Created attachment 671714 [details]
Diff for fix to bug

Description of problem:
ksvalidator will not produce any output if redirected to a file or pipe, but will if invoked with no redirection


Version-Release number of selected component (if applicable):
Present in origin/master (4305de8), and pykickstart-1.74.10-1.el6.noarch


How reproducible:
every time validating a kickstart when output is redirected.


Steps to Reproduce:
1. ksvalidator /tmp/test.ks | less
  
Actual results:
no output

Expected results:
output

Additional info:
Interestingly, it doesn't happen if I invoke 'ksvalidator -h|less', but it does when executing 'ksvalidator|less' (even though the output in both cases is the same when run without the pipe).

Seems to be an issue with ksvalidator calling os._exit(exitval) instead of sys.exit(exitval), which will flush buffers and cleanup as appropriate. Attached is a diff that fixes the bug.