test-http-proxy: redirect proxy stdout to /dev/null

This output hasn't been getting flushed, but would alter the log if it ever grew
large enough.  See 23b07333a8b2.

tests/test-http-proxy.t

@@ -8,7 +8,7 b''
   $ hg serve --config server.uncompressed=True -p $HGPORT -d --pid-file=hg.pid
   $ cat hg.pid >> $DAEMON_PIDS
   $ cd ..
-  $ tinyproxy.py $HGPORT1 localhost >proxy.log 2>&1 </dev/null &
+  $ tinyproxy.py $HGPORT1 localhost 2>proxy.log >/dev/null </dev/null &
   $ while [ ! -f proxy.pid ]; do sleep 0; done
   $ cat proxy.pid >> $DAEMON_PIDS
 

tests/tinyproxy.py

@@ -54,6 +54,7 b' class ProxyHandler (httpserver.basehttpr'
                          self.requestline, str(code), str(size),
                          ''.join([' %s:%s' % h for h in sorted(xheaders)]))
         # Flush for Windows, so output isn't lost on TerminateProcess()
+        sys.stdout.flush()
         sys.stderr.flush()
 
     def _connect_to(self, netloc, soc):