Patrick Griffis authored Oct 29, 2018 and Patrick Griffis committed Dec 11, 2018

Currently a new connection will not be attempted until the previous
one has timed out and as the current API only exposes a single
timeout value in practice it often means that it will wait 30 seconds
(or forever with 0 (the default)) on each connection.

This is unacceptable so we are now trying to follow the behavior
RFC 8305 recommends by making multiple connection attempts if
the connection takes longer than 250ms. The first connection
to make it to completion then wins.