Fix Audio from data without numpy on Python 3.

IPython/lib/display.py

@@ -159,16 +159,12 b' class Audio(DisplayObject):'
 
     @staticmethod
     def _validate_and_normalize_without_numpy(data):
-        # check that it is a "1D" list
-        idata = iter(data)  # fails if not an iterable
         try:
-            iter(idata.next())
+            maxabsvalue = float(max([abs(x) for x in data]))
+        except TypeError:
             raise TypeError('Only lists of mono audio are '
                 'supported if numpy is not installed')
-        except TypeError:
-            # this means it's not a nested list, which is what we want
-            pass
-        maxabsvalue = float(max([abs(x) for x in data]))
+
         scaled = [int(x/maxabsvalue*32767) for x in data]
         nchan = 1
         return scaled, nchan

IPython/lib/tests/test_display.py

@@ -19,6 +19,7 b' try:'
     import pathlib
 except ImportError:
     pass
+from unittest import mock
 
 # Third-party imports
 import nose.tools as nt
@@ -186,6 +187,17 b' def test_audio_from_file():'
 def test_audio_from_numpy_array():
     display.Audio(get_test_tone(), rate=44100)
 
+def test_audio_from_list_without_numpy():
+    # Simulate numpy not installed.
+    with mock.patch('numpy.array', side_effect=ImportError):
+        display.Audio(list(get_test_tone()), rate=44100)
+
+def test_audio_from_list_without_numpy_raises_for_nested_list():
+    # Simulate numpy not installed.
+    with mock.patch('numpy.array', side_effect=ImportError):
+        stereo_signal = [list(get_test_tone())] * 2
+        nt.assert_raises(TypeError, lambda: display.Audio(stereo_signal, rate=44100))
+
 def test_audio_from_numpy_array_without_rate_raises():
     nt.assert_raises(ValueError, display.Audio, get_test_tone())