issue with flet -> cl-flet change

[tacaswell]

PR #19 breaks refreshing buffers when changing branches. Reverting cl-flet -> flet fixes the problem. I will update later with more details + PR.

[tacaswell]

The error is:

git-after-working-dir-change: Invalid function: (buffer-refresh-func (buffer) (with-current-buffer buffer (revert-buffer t t)) (setq buffers-not-reverted (delq buffer buffers-not-reverted)) (incf num-buffers-refreshed))