If start_tls raises exception connection is retained in pool as connecting

[elupus]

I was investigating #117 since i'm hit with that. But since code has been very much refactored, it doesn't make sense anymore. However something similar may remain.

The following test fails for example. I don't think the stream should remain in pool if start_tls raises.

@pytest.mark.anyio
@unittest.mock.patch("httpcore.backends.mock.AsyncMockStream.start_tls")
async def test_connection_pool_with_exception_on_start(start_tls_mock: unittest.mock.MagicMock):
    """
    HTTP/1.1 requests that result in an exception should not be returned to the
    connection pool.
    """
    start_tls_mock.side_effect = Exception()
    network_backend = AsyncMockBackend([b"Wait, this isn't valid HTTP!"])

    async with AsyncConnectionPool(network_backend=network_backend) as pool:
        # Sending an initial request, which once complete will not return to the pool.
        with pytest.raises(Exception):
            await pool.request(
                "GET", "https://example.com/"
            )

        info = [repr(c) for c in pool.connections]
        assert info == []

[elupus]

For separate reference. I think the issue i was looking for might have been solved. The following test does indeed succeed now:

@pytest.mark.anyio
@unittest.mock.patch("httpcore.backends.mock.AsyncMockStream.aclose")
async def test_connection_pool_with_incomplete_data(aclose_mock: unittest.mock.MagicMock):
    """
    HTTP/1.1 requests that result in an exception should not be returned to the
    connection pool.
    """
    network_backend = AsyncMockBackend(
        [
            b"HTTP/1.1 200 OK\r\n",
            b"Content-Type: plain/text\r\n",
            b"Content-Length: 13\r\n",
            b"\r\n",
            b"",
        ]
    )

    async with AsyncConnectionPool(network_backend=network_backend) as pool:
        # Sending an initial request, which once complete will not return to the pool.
        with pytest.raises(Exception):
            await pool.request(
                "GET", "https://example.com/"
            )

        info = [repr(c) for c in pool.connections]
        assert info == []
        assert aclose_mock.call_count == 1

[elupus]

Anmoyingly issue reoccured: fix here #443