init: Fix misbehavior when core.sharedRepository = group that caused it to
enter an adjusted branch. (Reversion in version 8.20210630)
Commit 4b1b9d7a83 made init call
freezeContent in case there was a hook that could prevent writing in
situations where perms don't. But with the above git config, freezeContent
does not prevent write at all. So init needs to do what freezeContent does
with a non-shared git config.
Or init could check for that config, and skip the probing, since it
won't actually be preventing write to any files. But that would make init
too aware if details of Annex.Perms, and also would break if the git config
were changed after init.
Sponsored-by: Dartmouth College's Datalad project
