Windows only: search for Git's bundled ssh.exe in known locations

def _find_ssh_exe():
    '''
    Windows only: search for Git's bundled ssh.exe in known locations
    '''
    # Known locations for Git's ssh.exe in Windows
    globmasks = [os.path.join(os.getenv('SystemDrive'), os.sep,
                              'Program Files*', 'Git', 'usr', 'bin',
                              'ssh.exe'),
                 os.path.join(os.getenv('SystemDrive'), os.sep,
                              'Program Files*', 'Git', 'bin',
                              'ssh.exe')]
    for globmask in globmasks:
        ssh_exe = glob.glob(globmask)
        if ssh_exe and os.path.isfile(ssh_exe[0]):
            ret = ssh_exe[0]
            break
    else:
        ret = None

    return ret