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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`


"""set refs for the remote branch version
    This assumes the branch does not yet exist locally and is therefore also not checked out.
    Can't use git remote set-branches, as it is not available in git 1.7.1 (centos6)
    """
    branchref = "+refs/heads/%s:refs/heads/%s" % (version, version)
    branchref += ' +refs/heads/%s:refs/remotes/%s/%s' % (version, remote, version)
    cmd = "%s fetch --depth=%s %s %s" % (git_path, depth, remote, branchref)
    (rc, out, err) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        module.fail_json(msg="Failed to fetch branch from remote: %s" % version, stdout=out, stderr=err, rc=rc)
def switch_version(git_path, module, dest, remote, version, verify_commit, depth, gpg_whitelist):
    cmd = ''
    if version == 'HEAD':
        branch = get_head_branch(git_path, module, dest, remote)
        (rc, out, err) = module.run_command("%s checkout --force %s" % (git_path, branch), cwd=dest)
        if rc != 0:
            module.fail_json(msg="Failed to checkout branch %s" % branch,
                             stdout=out, stderr=err, rc=rc)