Unlike a plain `net/http/client.Do()`, requests made through client/request
use the `sendRequest` function, which parses the server response, and may
convert non-transport errors into errors (through `cli.checkResponseErr()`).
This means that we cannot assume that no reader was opened if an error is
returned.
This patch changes various locations where `ensureReaderClosed` was only
called in the non-error situation, and uses a `defer` to make sure it's
always called.
`ensureReaderClosed` itself already checks if the response's body was set,
so in situations where the error was due to a transport error, calling
`ensureReaderClosed` should be a no-op.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
