py3: suppress the output of open() using `and None`
This patch suppresses the output of open() on Python 3 as it does not return any
output on Python 2.
This makes test-diffstat.t pass on Python 3.5
Differential Revision: https://phab.mercurial-scm.org/D3128
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true