Merge pull request ipython#1716 from takluyver/verbose-tb

Fix for fake filenames in verbose traceback.

We use in our frames fake filenames of the type `<ipython....>`, and we relied on `abspath` throwing an `OSError` exception with them.  That is no longer the case, and it leads to verbose tracebacks not inspecting IPython frames correctly.

This fixes the issue by simply assuming that any file that starts/ends with `</>` can't be a normal python file, which is a sensible policy (for one thing, such names can't be imported).

IPython/core/ultratb.py

@@ -786,13 +786,19 @@ def nullrepr(value, repr=text_repr): return ''
         abspath = os.path.abspath
         for frame, file, lnum, func, lines, index in records:
             #print '*** record:',file,lnum,func,lines,index  # dbg
-            try:
-                file = file and abspath(file) or '?'
-            except OSError:
-                # if file is '<console>' or something not in the filesystem,
-                # the abspath call will throw an OSError.  Just ignore it and
-                # keep the original file string.
-                pass
+
+            if not file:
+                file = '?'
+            elif not(file.startswith("<") and file.endswith(">")):
+                # Guess that filenames like <string> aren't real filenames, so
+                # don't call abspath on them.                    
+                try:
+                    file = abspath(file)
+                except OSError:
+                    # Not sure if this can still happen: abspath now works with
+                    # file names like <string>
+                    pass
+
             link = tpl_link % file
             args, varargs, varkw, locals = inspect.getargvalues(frame)