Weird diffing

[canpolat]

When I test DirState on a directory of 2000+ files, I get a weird diff behavior. Here is my code (it's just a copy of your code in README):

PATH = "/my/path/here"

def main():
    d1 = Dir(PATH)
    state = DirState(d1)
    print("State 0: {}".format(len(state.state['files'])))

    json = state.to_json()

    d2 = Dir(PATH)
    state2 = DirState(d2)
    print("State 2: {}".format(len(state2.state['files'])))

    state1 = DirState.from_json(json)
    print("State 1: {}".format(len(state1.state['files'])))

    changes = state2 - state1
    print("Diff: {}".format(len(changes['created'])))

if __name__=='__main__':
    main()

And here is the output I get:

State 0: 2333
State 2: 2333
State 1: 2333
Diff: 1924

Can you spot a problem in my code? Or is it a subtle bug in DirState implementation? (I'm using dirtools 0.2.0 from PyPi).