InteractiveShell.object_inspect_text must return text

That's the whole point of it.

Adds object_inspect_mime for returning the mimebundle of formatted outputs,
which `_get_info` now returns.

IPython/core/interactiveshell.py

@@ -1579,6 +1579,14 b' class InteractiveShell(SingletonConfigurable):'
 
     def object_inspect_text(self, oname, detail_level=0):
         """Get object info as formatted text"""
+        return self.object_inspect_mime(oname, detail_level)['text/plain']
+
+    def object_inspect_mime(self, oname, detail_level=0):
+        """Get object info as a mimebundle of formatted representations.
+
+        A mimebundle is a dictionary, keyed by mime-type.
+        It must always have the key `'text/plain'`.
+        """
         with self.builtin_trap:
             info = self._object_find(oname)
             if info.found:

IPython/core/tests/test_interactiveshell.py

@@ -514,6 +514,12 b' class InteractiveShellTestCase(unittest.TestCase):'
         else:
             self.assertEqual(msg, 'IPython.core.tests.test_interactiveshell.DerivedInterrupt: foo\n')
 
+    def test_inspect_text(self):
+        ip.run_cell('a = 5')
+        text = ip.object_inspect_text('a')
+        self.assertIsInstance(text, unicode_type)
+
+
 class TestSafeExecfileNonAsciiPath(unittest.TestCase):
 
     @onlyif_unicode_paths