Task #9678: Use subprocess27 module to use poll() in Popen as well

CEP/Pipeline/framework/lofarpipe/support/subprocessgroup.py

-import subprocess
 import select
 import os
 import signal
@@ -6,6 +5,14 @@ import fcntl
 import time
 from lofarpipe.support.lofarexceptions import PipelineException
 
+# subprocess is broken in python <=2.6. It does not work for fds > 1024 for example.
+try:
+    import subprocess27 as subprocess
+    print >> sys.stderr, __file__, ": Using Python 2.7 subprocess module!"
+except ImportError:
+    import subprocess
+    print >> sys.stderr, __file__, ": Using default subprocess module!"
+
 class SubProcess(object):
     STDOUT = 1
     STDERR = 2