Fix error message when using exclusion

pylib/gyp/input.py

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from compiler.ast import Const
 from compiler.ast import Dict
 from compiler.ast import Discard
 from compiler.ast import List
 from compiler.ast import Module
 from compiler.ast import Node
@@ skipping 2260 matching lines @@
 
     list_key = key[:-1]
     if list_key not in the_dict:
       # This happens when there's a list like "sources!" but no corresponding
       # "sources" list.  Since there's nothing for it to operate on, queue up
       # the "sources!" list for deletion now.
       del_lists.append(key)
       continue
 
     if not isinstance(the_dict[list_key], list):
+      value = the_dict[list_key]
       raise ValueError, name + ' key ' + list_key + \
                         ' must be list, not ' + \
                         value.__class__.__name__ + ' when applying ' + \
                         {'!': 'exclusion', '/': 'regex'}[operation]
 
     if not list_key in lists:
       lists.append(list_key)
 
   # Delete the lists that are known to be unneeded at this point.
   for del_list in del_lists:
@@ skipping 509 matching lines @@
     ValidateRunAsInTarget(target, target_dict, build_file)
     ValidateActionsInTarget(target, target_dict, build_file)
 
   # Generators might not expect ints.  Turn them into strs.
   TurnIntIntoStrInDict(data)
 
   # TODO(mark): Return |data| for now because the generator needs a list of
   # build files that came in.  In the future, maybe it should just accept
   # a list, and not the whole data dict.
   return [flat_list, targets, data]