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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`


if refspecs:
            
            
            
            
            fetch_cmd.extend(['--depth', str(depth)])
    if not depth or not refspecs:
        
        
        if bare:
            refspecs = ['+refs/heads/*:refs/heads/*', '+refs/tags/*:refs/tags/*']
        else:
            
            if git_version_used >= LooseVersion('1.9'):
                fetch_cmd.append('--tags')
            else:
                
                commands.append((fetch_str, fetch_cmd + [remote]))
                refspecs = ['+refs/tags/*:refs/tags/*']
        if refspec:
            refspecs.append(refspec)
    if force:
        fetch_cmd.append('--force')
    fetch_cmd.extend([remote])
    commands.append((fetch_str, fetch_cmd + refspecs))
    for (label, command) in commands:
        (rc, out, err) = module.run_command(command, cwd=dest)
        if rc != 0:
            module.fail_json(msg="Failed to %s: %s %s" % (label, out, err), cmd=command)
def submodules_fetch(git_path, module, remote, track_submodules, dest):