check-code: added check for reduce usage

check-code: check for tuple parameter unpacking (missing in py3k)

removed exception args indexing (not supported by py3k) Py3k removed __getitem__ for exception classes. The correct way of getting the exception arguments is by using the args method.

util: use fakebuffer as buffer in py3k There's no buffer type in py3k, util.py has a function, called fakebuffer, that implements a similar API. This patch implements fakebuffer as a memoryview wrapper in py3k.

util: improved the check for the existence of the 'buffer' builtin 2to3 is unable to translate '__builtin__' calls to 'builtins' when hasattr is used (as in hasattr(__builtin__, buffer)). Translating the check to the format try: whatever except NameError # define whatever __builtin__.whatever = whatever is a correct way of checking for the name and has the benefit of being translated by 2to3. This patch implements the same idea for the aforementioned example.

record: removed 'has_key' usage Py3k has removed the dictionary has_key method. This patch implements a one argument function that can be used as a callback by hg.revert in the record extension.