Return non-zero when group membership change fails, no empty fail list.

There is no point (and it is confusing) to print an empty list when
modifying group membership fails, so suppress it.

If any membership change fails we should return non-zero.

tickets 271, 273, 274

ipalib/frontend.py

@@ -844,6 +844,22 @@ class Command(HasParam):
                 continue
             yield param
 
+    def number_failed(self, failed):
+        """
+        Return the number of entries in the failed output parameter.
+
+        This is used to determine whether the failed members should be
+        displayed and what the return value should be.
+        """
+        num_failed = 0
+        for f in failed:
+            if type(failed[f]) is dict:
+                num_failed = num_failed + self.number_failed(failed[f])
+            else:
+                num_failed = num_failed + len(failed[f])
+
+        return num_failed
+
     def output_for_cli(self, textui, output, *args, **options):
         """
         Generic output method. Prints values the output argument according
@@ -860,6 +876,8 @@ class Command(HasParam):
         if not isinstance(output, dict):
             return
 
+        rv = 0
+
         order = [p.name for p in self.output_params()]
         if options.get('all', False):
             order.insert(0, 'dn')
@@ -878,6 +896,13 @@ class Command(HasParam):
                 continue
             result = output[o]
 
+            if o.lower() == 'failed':
+                if self.number_failed(result) == 0:
+                    # Don't display an empty failed list
+                    continue
+                else:
+                    # Return an error to the shell
+                    rv = 1
             if isinstance(outp, ListOfEntries):
                 textui.print_entries(result, order, labels, print_all)
             elif isinstance(result, (tuple, list)):
@@ -898,6 +923,7 @@ class Command(HasParam):
             elif isinstance(result, int):
                 textui.print_count(result, '%s %%d' % unicode(self.output[o].doc))
 
+        return rv
 
 class LocalOrRemote(Command):
     """