breaks build

««« original CL description
http: close connection after printing panic stack trace
In a testing situation, it's possible for a local http
server to panic and the test exit without the stack trace
ever being printed.
Fixes #2480.

R=rsc, bradfitz
CC=golang-dev
https://golang.org/cl/5414048

»»»

R=bradfitz
CC=golang-dev
https://golang.org/cl/5482061