Whitelist file extensions that are safe to tokenise.

IPython/core/ultratb.py

@@ -825,13 +825,16 b' class VerboseTB(TBTools):'
                     call = tpl_call_fail % func
             
             # Don't attempt to tokenize binary files.
-            if file.endswith(('.so', '.pyd', '.dll')):
-                frames.append('%s %s\n' % (link,call))
-                continue
-
-            def linereader(file=file, lnum=[lnum], getline=linecache.getline):
+            if not file.endswith(('.py', '.pyw')):
                 if file.endswith(('.pyc','.pyo')):
+                    # Look up the corresponding source file.
                     file = pyfile.source_from_cache(file)
+                else:
+                    # .so, .pyd, etc.
+                    frames.append('%s %s\n' % (link,call))
+                    continue
+
+            def linereader(file=file, lnum=[lnum], getline=linecache.getline):
                 line = getline(file, lnum[0])
                 lnum[0] += 1
                 return line