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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`


type: path
        required: true
    version:
        description:
            - What version of the repository to check out. This can be
              the literal string C(HEAD), a branch name, a tag name.
              It can also be a I(SHA-1) hash, in which case I(refspec) needs
              to be specified if the given revision is not already available.
        type: str
        default: "HEAD"
    accept_hostkey:
        description:
            - If C(yes), ensure that "-o StrictHostKeyChecking=no" is
              present as an ssh option.
        type: bool
        default: 'no'
        version_added: "1.5"
    accept_newhostkey:
        description:
            - As of OpenSSH 7.5, "-o StrictHostKeyChecking=accept-new" can be
              used which is safer and will only accepts host keys which are
              not present or are the same. if C(yes), ensure that
              "-o StrictHostKeyChecking=accept-new" is present as an ssh option.
        type: bool
        default: 'no'
        version_added: "2.12"
    ssh_opts:
        description:
            - Creates a wrapper script and exports the path as GIT_SSH
              which git then automatically uses to override ssh arguments.