Fix a problem with authkeys perms when REPO_UMASK is too loose.
(To duplicate it, run a fresh, non-root install, and when gl-setup pops
up an editor, change the REPO_UMASK to 0007 (from the default 0077).
You'll find that ~/.ssh/authorized_keys now has g+w set, causing sshd to
refuse key-based access.)
And before you ask, even though gl-setup does it, I won't fiddle with
the permissions of an existing file in *this* code. (gl-setup is run
manually by the admin, this one gets run on every push).
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Side note: 9ad7ea4 was somewhat forced on me, and I didn't really agree
with parts of it. I have no idea why I gave in so easily, but it won't
happen again!
c7d95293dd