http: don't hang on redirect with length + connection close

http: don't hang on redirect with length + connection close

Most servers who close the connection do not send a content-length as
this is redundant information usually, but some might and while testing
with our server and with 'aptwebserver::response-header::Connection' set
to 'close' I noticed that http hangs after a redirect in such cases, so
if we have the information, just use it instead of discarding it.