http error response: stop sending when error is received

When libcurl has said to the server that there's a POST or PUT coming
(with a content-length and all) it has to either deliver that amount of
data or it needs to close the connection before trying a second request.

Adds test case 1129, 1130 and 1131

The bug report is about when used with 100-continue, but the change is
more generic.

Bug: http://curl.haxx.se/mail/lib-2011-06/0191.html
Reported by: Steven Parkes