Don't catch ImportError when trying to unpack module functions

If the ImportError is encountered, it is more informative to raise it rather than hide it, possibly resulting in confusing NameErrors due to the import failure.

IPython/utils/pickleutil.py

@@ -98,11 +98,7 b' class CannedFunction(CannedObject):'
     def get_object(self, g=None):
         # try to load function back into its module:
         if not self.module.startswith('__'):
-            try:
                 __import__(self.module)
-            except ImportError:
-                pass
-            else:
                 g = sys.modules[self.module].__dict__
 
         if g is None: