<!--- Verify first that your feature was not already discussed on GitHub -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
The `ssh_opts` parameter relies on setting environment variables for git, such as GIT_SSH. Git did not recognize this environment variable until version 2.3.0 (see https://git-scm.com/docs/git/2.3.0), and many contemporary OSes (RHEL 7, CentOS7) include older versions of Git (1.8.3.1).

It would be useful to provide a warning in this case, similar to the warning for the `depth` parameter. E.g. "Your git version is too old to support the ssh_opts argument."

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
git.py
source control, git module

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
It would save users time when trying to troubleshoot failed git connections via SSH.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- name: clone a git repo
  git:
    repo: git@github.com:cherdt/hello_ansible.git
    dest: /opt/hello_ansible
    version: master
    ssh_opts: "{{-o IdentityFile=github_id_rsa}}"
```

<!--- HINT: You can also paste gist.github.com links for larger files -->

'''Return URL of remote source for repo.'''
    command = [git_path, 'ls-remote', '--get-url', remote]
    (rc, out, err) = module.run_command(command, cwd=dest)
    if rc != 0:
        
        
        return None
    return to_native(out).rstrip('\n')
def set_remote_url(git_path, module, repo, dest, remote):
    ''' updates repo from remote sources '''
    
    remote_url = get_remote_url(git_path, module, dest, remote)
    if remote_url == repo or unfrackgitpath(remote_url) == unfrackgitpath(repo):
        return False
    command = [git_path, 'remote', 'set-url', remote, repo]
    (rc, out, err) = module.run_command(command, cwd=dest)
    if rc != 0:
        label = "set a new url %s for %s" % (repo, remote)
        module.fail_json(msg="Failed to %s: %s %s" % (label, out, err))
    
    
    return remote_url is not None
def fetch(git_path, module, repo, dest, version, remote, depth, bare, refspec, git_version_used, force=False):