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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`


branches = get_branches(git_path, module, dest)
    for branch in branches:
        if branch.startswith('* ') and ('no branch' in branch or 'detached from' in branch or 'detached at' in branch):
            return True
    return False
def get_repo_path(dest, bare):
    if bare:
        repo_path = dest
    else:
        repo_path = os.path.join(dest, '.git')
    
    
    if os.path.isfile(repo_path):
        with open(repo_path, 'r') as gitfile:
            data = gitfile.read()
        ref_prefix, gitdir = data.rstrip().split('gitdir: ', 1)
        if ref_prefix:
            raise ValueError('.git file has invalid git dir reference format')
        
        if os.path.isabs(gitdir):
            repo_path = gitdir
        else:
            
            repo_path = os.path.join(dest, gitdir)
        if not os.path.isdir(repo_path):
            raise ValueError('%s is not a directory' % repo_path)
    return repo_path
def get_head_branch(git_path, module, dest, remote, bare=False):