[4.1] 0d6d6cb Use the idle read timeout only on empty requests

[Martin Blix Grydeland]

commit 0d6d6cbf2e83a0c1cea8a353b5920fc6d186f9b7
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Mon Nov 13 15:51:11 2017 +0100

    Use the idle read timeout only on empty requests
    
    We only want to return the connection early to the waiter when the
    request is empty. Correct the read timeout calculation to reflect
    that.
    
    Thanks to Stackpath for helping to debug this issue.
    
    Fixes: #2492

diff --git a/bin/varnishd/cache/cache_session.c b/bin/varnishd/cache/cache_session.c
index 8c9c3b6..8ab7d51 100644
--- a/bin/varnishd/cache/cache_session.c
+++ b/bin/varnishd/cache/cache_session.c
@@ -244,7 +244,7 @@ SES_RxStuff(struct http_conn *htc, htc_complete_f *func,
 			WRONG("htc_status_e");
 
 		tmo = tn - now;
-		if (!isnan(ti) && ti < tn)
+		if (!isnan(ti) && ti < tn && hs == HTC_S_EMPTY)
 			tmo = ti - now;
 		i = (htc->ws->r - htc->rxbuf_e) - 1;	/* space for NUL */
 		if (i <= 0) {