doc: simplify a go1.3 change description

LGTM=r
R=rsc, r
CC=golang-codereviews
https://golang.org/cl/87750043

doc/go1.3.html

@@ -354,8 +354,7 @@ has a <code>KeepAlive</code> option to specify a keep-alive period for the conne
 The <a href="/pkg/net/http/"><code>net/http</code></a> package's 
 <a href="/pkg/net/http/#Transport"><code>Transport</code></a>
 now closes <a href="/pkg/net/http/#Request"><code>Request.Body</code></a>
-consistently, even on errors. Previously it was closed on success and
-closed on some errors, sometimes depending on timing.
+consistently, even on error.
 </li>
 
 <li> TODO: net: enable fast socket creation using SOCK_CLOEXEC and Accept4 on FreeBSD 10 (69100043)</li>