If the SerialBuffers can just feed the same line queue, then we don't need the extra threads reading line queues into a new merged line queue. Less python threading code is always better. Plus, now we can pass args to SerialBuffer.lines() for timeout/phase. Acked-by: Juan A. Suarez <jasuarez@igalia.com> Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17096>