CL 140357 caused HTTP/2 connections to be put in the idle pool, but
failed to properly guard the trace.GotConn call in getConn. dialConn
returns a minimal persistConn with conn == nil for HTTP/2 connections.
This persistConn was then returned from queueForIdleConn and caused the
httptrace.GotConnInfo passed into GotConn to have a nil Conn field.
HTTP/2 connections call GotConn themselves so leave it for HTTP/2 to call
GotConn as is done directly below.
Reviewed-by: Michael Fraenkel <email@example.com>
Reviewed-by: Brad Fitzpatrick <firstname.lastname@example.org>
Run-TryBot: Brad Fitzpatrick <email@example.com>
TryBot-Result: Gobot Gobot <firstname.lastname@example.org>
(cherry picked from commit 582d519)
Reviewed-by: Daniel Martí <email@example.com>
Reviewed-by: Bryan C. Mills <firstname.lastname@example.org>
Run-TryBot: Daniel Martí <email@example.com>