Merge branch 'jn/ssh-wrappers'

The ssh-variant 'simple' introduced earlier broke existing installations by not passing --port/-4/-6 and not diagnosing an attempt to pass these as an error. Instead, default to automatically detect how compatible the GIT_SSH/GIT_SSH_COMMAND is to OpenSSH convention and then error out an invocation to make it easier to diagnose connection errors. * jn/ssh-wrappers: connect: correct style of C-style comment ssh: 'simple' variant does not support --port ssh: 'simple' variant does not support -4/-6 ssh: 'auto' variant to select between 'ssh' and 'simple' connect: split ssh option computation to its own function connect: split ssh command line options into separate function connect: split git:// setup into a separate function connect: move no_fork fallback to git_tcp_connect ssh test: make copy_ssh_wrapper_as clean up after itself