Fix broken 'binary content' in browseable API

Author: tomchristie

rest_framework/renderers.py

@@ -332,8 +332,8 @@ def get_content(self, renderer, data,
         renderer_context['indent'] = 4
         content = renderer.render(data, accepted_media_type, renderer_context)
 
-        if not isinstance(content, six.text_type):
-            return '[%d bytes of binary content]'
+        if not all(char in string.printable for char in content):
+            return '[%d bytes of binary content]' % len(content)
 
         return content