Re: [PATCH 3/5] ssh: 'auto' variant to select between 'ssh' and 'simple'

Jonathan Nieder [off-list ref] writes:

 1. First, check whether $GIT_SSH supports OpenSSH options by running

	$GIT_SSH -G <options> <host>

    This returns status 0 and prints configuration in OpenSSH if it
    recognizes all <options> and returns status 255 if it encounters
    an unrecognized option.  A wrapper script like

	exec ssh -- "$@"

    would fail with

	ssh: Could not resolve hostname -g: Name or service not known

    , correctly reflecting that it does not support OpenSSH options.

Two comments.

 * It would have been really nicer if the push_ssh_options() got
   split from its caller in a separate preparatory [PATCH 2.5/5].

 * Use of -G for auto-detection is clever and cute, but do we know
   how safe it would be in the real world?  What worries me the most
   is "myssh -G localhost" (no extra options) that does not fit our
   expectation on "-G" to either exit immediately with an error when
   it is not understood, or to exit like OpenSSH does, and instead
   successfully makes a connection and gets stuck.