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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`


import os
import re
import shlex
import stat
import sys
import shutil
import tempfile
from ansible.module_utils.compat.version import LooseVersion
from ansible.module_utils._text import to_native, to_text
from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.common.locale import get_best_parsable_locale
from ansible.module_utils.common.process import get_bin_path
from ansible.module_utils.six import b, string_types
def relocate_repo(module, result, repo_dir, old_repo_dir, worktree_dir):
    if os.path.exists(repo_dir):
        module.fail_json(msg='Separate-git-dir path %s already exists.' % repo_dir)
    if worktree_dir:
        dot_git_file_path = os.path.join(worktree_dir, '.git')
        try:
            shutil.move(old_repo_dir, repo_dir)
            with open(dot_git_file_path, 'w') as dot_git_file:
                dot_git_file.write('gitdir: %s' % repo_dir)
            result['git_dir_before'] = old_repo_dir
            result['git_dir_now'] = repo_dir
        except (IOError, OSError) as err:
            
            if os.path.exists(repo_dir):
                shutil.move(repo_dir, old_repo_dir)
            module.fail_json(msg=u'Unable to move git dir. %s' % to_text(err))
def head_splitter(headfile, remote, module=None, fail_on_error=False):