HttpClientTests: Open OutputStream in try-with-resource

Change-Id: Ib690b0af6d562765f43ad54d3855200a17eaa90b
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.http.test/tst/org/eclipse/jgit/http/test/HttpClientTests.java

@@ -419,12 +419,12 @@ public class HttpClientTests extends HttpTestCase {
 		// properly. Tests for other commands go in
 		// UploadPackTest.java.
 
-		OutputStream os = c.getOutputStream();
+		try (OutputStream os = c.getOutputStream()) {
 			PacketLineOut pckOut = new PacketLineOut(os);
 			pckOut.writeString("command=ls-refs");
 			pckOut.writeDelim();
 			pckOut.end();
-		os.close();
+		}
 
 		PacketLineIn pckIn = new PacketLineIn(c.getInputStream());