NdMapping.label looks at first element instead of iterating recursively

holoviews/core/ndmapping.py

@@ -13,7 +13,8 @@
 
 from . import traversal, util
 from .dimension import OrderedDict, Dimension, Dimensioned, ViewableElement
-from .util import unique_iterator, sanitize_identifier, dimension_sort, group_select, iterative_select, basestring, wrap_tuple, process_ellipses
+from .util import (unique_iterator, sanitize_identifier, dimension_sort,
+                   basestring, wrap_tuple, process_ellipses)
 
 
 class item_check(object):
@@ -778,10 +779,8 @@ def label(self):
         if self._label:
             return self._label
         else:
-            labels = {v.label for v in self.values()
-                      if not v._auxiliary_component}
-            if len(labels) == 1:
-                return list(labels)[0]
+            if len(self):
+                return next(iter(self.data)).label
             else:
                 return ''