"Cannot insert multiple commands into prepared statement" issue while executing query with params

(python 3.5.1, asyncpg 0.5.4)

Consider the next code

import asyncpg
import asyncio

async def run():
    con = await asyncpg.connect(user="coldmind", database="test")
    await con.execute('SELECT ($1); SELECT 2;', 1)
asyncio.get_event_loop().run_until_complete(run())

The executing fails with asyncpg.exceptions.PostgresSyntaxError: cannot insert multiple commands into a prepared statement error, while the another example (without passing params to the query) works well with multiple commands:

import asyncpg
import asyncio


async def run():
    con = await asyncpg.connect(user="coldmind", database="test")
    await con.execute('SELECT 1; SELECT 2;')
asyncio.get_event_loop().run_until_complete(run())

Why is the first example using a prepared statement instead of executing it?

從 con.execute 進入點開始，執行 issue 中的兩個 Python 範例，以比較參數化查詢和非參數化查詢。追蹤參數如何影響執行，然後確立多個命令的預期行為，並記錄或測試由此得出的決定。