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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`


tags = []
    cmd = [git_path, 'for-each-ref', 'refs/tags/', '--format', '%(objecttype):%(refname:short)']
    (rc, out, err) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        module.fail_json(msg="Could not determine tag data - received %s" % out, stdout=out, stderr=err)
    for line in to_native(out).split('\n'):
        if line.strip():
            tagtype, tagname = line.strip().split(':')
            if tagtype == 'tag':
                tags.append(tagname)
    return tags
def is_remote_branch(git_path, module, dest, remote, version):
    cmd = '%s ls-remote %s -h refs/heads/%s' % (git_path, remote, version)
    (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
    if to_native(version, errors='surrogate_or_strict') in out:
        return True
    else:
        return False
def is_local_branch(git_path, module, dest, branch):
    branches = get_branches(git_path, module, dest)
    lbranch = '%s' % branch
    if lbranch in branches:
        return True
    elif '* %s' % branch in branches:
        return True
    else:
        return False
def is_not_a_branch(git_path, module, dest):