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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 = "%s reset --hard %s/%s --" % (git_path, remote, branch)
    else:
        
        if is_remote_branch(git_path, module, dest, remote, version):
            if depth and not is_local_branch(git_path, module, dest, version):
                
                
                
                set_remote_branch(git_path, module, dest, remote, version, depth)
            if not is_local_branch(git_path, module, dest, version):
                cmd = "%s checkout --track -b %s %s/%s" % (git_path, version, remote, version)
            else:
                (rc, out, err) = module.run_command("%s checkout --force %s" % (git_path, version), cwd=dest)
                if rc != 0:
                    module.fail_json(msg="Failed to checkout branch %s" % version, stdout=out, stderr=err, rc=rc)
                cmd = "%s reset --hard %s/%s" % (git_path, remote, version)
        else:
            cmd = "%s checkout --force %s" % (git_path, version)
    (rc, out1, err1) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        if version != 'HEAD':
            module.fail_json(msg="Failed to checkout %s" % (version),
                             stdout=out1, stderr=err1, rc=rc, cmd=cmd)
        else:
            module.fail_json(msg="Failed to checkout branch %s" % (branch),
                             stdout=out1, stderr=err1, rc=rc, cmd=cmd)
    if verify_commit:
        verify_commit_sign(git_path, module, dest, version, gpg_whitelist)
    return (rc, out1, err1)
def verify_commit_sign(git_path, module, dest, version, gpg_whitelist):