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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`


cmd = [git_path, 'submodule', 'status']
            (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
            if rc != 0:
                module.fail_json(msg='Failed to retrieve submodule status: %s' % out + err)
            for line in out.splitlines():
                if line[0] != ' ':
                    changed = True
                    break
    return changed
def submodule_update(git_path, module, dest, track_submodules, force=False):
    ''' init and update any submodules '''
    
    params = get_submodule_update_params(module, git_path, dest)
    
    if not os.path.exists(os.path.join(dest, '.gitmodules')):
        return (0, '', '')
    cmd = [git_path, 'submodule', 'sync']
    (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
    if 'remote' in params and track_submodules:
        cmd = [git_path, 'submodule', 'update', '--init', '--recursive', '--remote']
    else:
        cmd = [git_path, 'submodule', 'update', '--init', '--recursive']
    if force:
        cmd.append('--force')
    (rc, out, err) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        module.fail_json(msg="Failed to init/update submodules: %s" % out + err)
    return (rc, out, err)
def set_remote_branch(git_path, module, dest, remote, version, depth):