Broken Async::Promise from Http::ResponseWriter::send()

[miketsts]

The promise returned from Http::ResponseWriter::send() doesn't call the success callback. I've written a unit test and run the git bisect session which resulted in:

6e0710533f5363d658c63047bf976808fe55e2f7 is the first bad commit
commit 6e0710533f5363d658c63047bf976808fe55e2f7
Author: Arthur de Araújo Farias <[email protected]>
Date:   Fri Feb 22 01:04:50 2019 +0100

    Fixing connection handling problem without modifying request object
    
    Fixes #333

 src/common/http.cc | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

My test is very similar to the example appearing in http://pistache.io/guide/#asynchronous-http-programming, but modified slightly in order to be able to check a test assertion.

The test is attached. Feel free to modify it if necessary.

http_async_test.diff.txt