Ticket #216: Don't sort None value

In Shine.CLI.Display, instead of returning None when sorting
without sorting parameter, just don't sort at all.
Avoid trying to sort and compare None value with is no more
sortable.

lib/Shine/CLI/Display.py

@@ -156,17 +156,10 @@ def fieldvals(comp):
                comps.groupby(key=fieldvals) ]
 
     # Sort
-    def sorter(compgrp):
-        """
-        Sort grplist based on provided sort_key for the first element of
-        compgrp.
-        """
-        (first, _) = compgrp
-        if sort_key is None:
-            return None
-        return sort_key(first)
-
-    for first, compgrp in sorted(grplst, key=sorter):
+    if sort_key is not None:
+        grplst.sort(key=lambda group: sort_key(group[0]))
+
+    for first, compgrp in grplst:
 
         # Get component fields
         fields = _get_fields(first, pat_fields)