iter_change_type can't get the "M" type

[alexazhou]

I have modify a file, use command "git status" can see it. but i can't use the iter_change_type of GitPython to find it out.

AlexaZhou$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   LICENSE

AlexaZhou$
AlexaZhou$

I can see it in the diff list, but can't get it from iter_change_type.

>>> repo = git.Repo('./')
>>> diff = repo.index.diff(None)
>>> 
>>> list( diff )
[<git.diff.Diff object at 0x1030ad348>]
>>> 
>>> list(diff.iter_change_type('A'))
[]
>>> list(diff.iter_change_type('D'))
[]
>>> list(diff.iter_change_type('R'))
[]
>>> list(diff.iter_change_type('M'))
[]
>>> 
>>> tmp = diff[0]
>>> tmp.a_blob
<git.Blob "65c5ca88a67c30becee01c5a8816d964b03862f9">
>>> 
>>> tmp.b_blob
>>> 
>>> tmp.b_blob == None
True
>>> 
>>> 

when I use GitPython 1.0.1 it seems work right. But i can't work after i upgrede to GitPython 2.0.7

Help you can fix it.