Split a host:port string into (host, int(port)) pair.

def partition_node(node):
    """Split a host:port string into (host, int(port)) pair."""
    host = node
    port = 27017
    idx = node.rfind(':')
    if idx != -1:
        host, port = node[:idx], int(node[idx + 1:])
    if host.startswith('['):
        host = host[1:-1]
    return host, port