Breaks in python 3.4.3

[henrahmagix]

Traceback (most recent call last):
  File "/Users/henry/git-browse/bin/git-browse", line 22, in <module>
    browser.run()
  File "/Users/henry/git-browse/bin/../gitbrowse/ui.py", line 146, in run
    self.command_input.edit(recurse=True)
  File "/Users/henry/git-browse/bin/../gitbrowse/ui.py", line 408, in edit
    data = super(ModalTextbox, self).edit(validate=self._process_key)
  File "/Users/henry/.pyenv/versions/3.4.3/lib/python3.4/curses/textpad.py", line 169, in edit
    ch = validate(ch)
  File "/Users/henry/git-browse/bin/../gitbrowse/ui.py", line 443, in _process_key
    self.delegate.textbox_command(self, key, prefix)
  File "/Users/henry/git-browse/bin/../gitbrowse/ui.py", line 108, in textbox_command
    method(prefix)
  File "/Users/henry/git-browse/bin/../gitbrowse/browser.py", line 104, in prev_commit
    self._move_commit('prev')
  File "/Users/henry/git-browse/bin/../gitbrowse/browser.py", line 86, in _move_commit
    mapping = self.file_history.line_mapping(start, finish)
  File "/Users/henry/git-browse/bin/../gitbrowse/git.py", line 151, in line_mapping
    forward, backward = self._build_line_mappings(start, finish)
  File "/Users/henry/git-browse/bin/../gitbrowse/git.py", line 213, in _build_line_mappings
    start_range = map(int, headers[0])
TypeError: 'map' object is not subscriptable

2.7.10 works though. Perhaps add version requirement to the readme?