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##### SUMMARY

The Git module encourages use of `StrictHostKeyChecking=no` with SSH, which makes the connection vulnerable to a MITM attack.

##### ISSUE TYPE

OpenSSH 7.5+ (2017-03-20) added a safer option which automatically accepts the key on first use but will not allow a MITM on subsequent connections: `StrictHostKeyChecking=accept-new` 

https://man.openbsd.org/ssh_config#StrictHostKeyChecking

It would be great if Ansible encouraged use of that mode by default in the documentation and to implement features such as the Git module's [`accept_hostkey`](https://github.com/ansible/ansible/blob/323d2adfcce9a53e906c2c4a40f6ac5fb32a0e68/lib/ansible/modules/git.py#L1103-L1108) feature.

##### ANSIBLE VERSION

```paste below
N/A
```

##### COMPONENT NAME
* `/modules/source_control/git.py`


''' samples the version of the git repo '''
    cmd = "%s rev-parse %s" % (git_path, ref)
    rc, stdout, stderr = module.run_command(cmd, cwd=dest)
    sha = to_native(stdout).rstrip('\n')
    return sha
def ssh_supports_acceptnewhostkey(module):
    try:
        ssh_path = get_bin_path('ssh')
    except ValueError as err:
        module.fail_json(
            msg='Remote host is missing ssh command, so you cannot '
            'use acceptnewhostkey option.', details=to_text(err))
    supports_acceptnewhostkey = True
    cmd = [ssh_path, '-o', 'StrictHostKeyChecking=accept-new', '-V']
    rc, stdout, stderr = module.run_command(cmd)
    if rc != 0:
        supports_acceptnewhostkey = False
    return supports_acceptnewhostkey
def get_submodule_versions(git_path, module, dest, version='HEAD'):