…#1250)

…s group (#1255)

…endencies group (#1261)

`escape_timedelta` produced the wrong SQL literal for a negative
`timedelta`. Python normalizes a negative `timedelta` so
`seconds`/`microseconds` are non-negative and the sign lives entirely in
`days`, but `escape_timedelta` decomposed the always-positive `seconds`
and applied the sign only through `days*24`. A negative value therefore
came out with complemented sub-hour fields — `-timedelta(minutes=30)`
escaped to `'-1:30:00'` (-5400s) instead of `'-00:30:00'`.

Co-authored-by: Inada Naoki <songofacandy@gmail.com>

Read the OK packet just after sending the EOF (enpty) packet.