Fix assertion in SmartClientSmartServerTest.testPush_CreateBranch()

This assertion only defined a message but didn't assert anything.

Change-Id: I0914642b64b69dc4e3ec24acbf8052f9171613d8
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -610,7 +610,7 @@ public class SmartClientSmartServerTest extends HttpTestCase {
 		fsck(remoteRepository, Q);
 
 		final ReflogReader log = remoteRepository.getReflogReader(dstName);
-		assertNotNull("has log for " + dstName);
+		assertNotNull("has log for " + dstName, log);
 
 		final ReflogEntry last = log.getLastEntry();
 		assertNotNull("has last entry", last);