Re: [PATCH v2] clone: fix segfault when using --revision and v0/v1 protocol

Hi Junio and thanks for your time!

While your change may skip the code that segfaults, wouldn't it also
stop noticing a broken case where .peer_ref should have been set but
didn't, even when --revision=<rev> parameter is not used in the
command invocation?  IOW, it is better to segfault and draw attention
by Git developers when a valid input is given by the end user and our
code misbehaves (e.g., and fails to to set .peer_ref as it should).

I totally agree with you.

Wouldn't the correct fix be more like the following?

- split out parts from update_remote_refs() that are needed even in
  option_rev mode into a separate helper function, and call that
  from cmd_clone().

- make the call to update_remote_refs() conditional---specifically,
  we shouldn't be calling it when option_rev is in effect.

Do we have another fix to make a conditional call to `find_ref_by_name()`
when `option_rev` is in effect? Because from the doc of `--revision`,
"... and detach `HEAD` to_<rev>_. ...", that means we don't need to
know where the real HEAD points to?

Also, isn't this something we can specify the expected behaviour in
tests?  Not only we want to ensure that nothing segfaults, we would
want to make sure that the resulting repository has no refs and HEAD
is detached at the specified revision.

I'll add several tests to cover the bug after we make sure how to fix it.