user: lock authorized_keys file
user: lock authorized_keys file

os.OpenFile() won't allow os.O_CREATE and os.O_EXCL together. I will
adapt fs/testing.

marcelometal/gandalf,gleez/gandalf,scorphus/gandalf,scorphus/gandalf,marcelometal/gandalf,marcelometal/gandalf,flaviamissi/gandalf,gleez/gandalf,gleez/gandalf,tsuru/gandalf,flaviamissi/gandalf,tsuru/gandalf