Skip logging stack trace on corrupt objects

Instead of dumping a full stack trace when a client sends an invalid
commit, record only a short line explaining the attempt:

  Cannot receive Invalid commit c0ff33...: invalid author into /tmp/jgit.git

The text alone is sufficient to explain the problem and the stack
trace does not lend any additional useful information. ObjectChecker
is quite clear about its rejection cases.

Change-Id: Ifc8cf06032489dc6431be1ba66101cf3d4299218

org.eclipse.jgit.http.server/resources/org/eclipse/jgit/http/server/HttpServerText.properties

 parameterNotSet=Parameter {0} not set
 pathForParamNotFound={0} (for {1}) not found
 pathNotSupported={0} not supported
+receivedCorruptObject=Cannot receive {0} into {1}
 repositoryAccessForbidden=Git access forbidden
 repositoryNotFound=Git repository not found
 servletAlreadyInitialized=Servlet already initialized

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/HttpServerText.java

 	/***/ public String parameterNotSet;
 	/***/ public String pathForParamNotFound;
 	/***/ public String pathNotSupported;
+	/***/ public String receivedCorruptObject;
 	/***/ public String repositoryAccessForbidden;
 	/***/ public String repositoryNotFound;
 	/***/ public String servletAlreadyInitialized;

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/ReceivePackServlet.java

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.errors.UnpackException;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.transport.InternalHttpServerGlue;
 
 			rp.receive(getInputStream(req), out, null);
 			out.close();
+		} catch (CorruptObjectException e ) {
+			// This should be already reported to the client.
+			getServletContext().log(MessageFormat.format(
+					HttpServerText.get().receivedCorruptObject,
+					e.getMessage(),
+					ServletUtils.identify(rp.getRepository())));
+			consumeRequestBody(req);
+			out.close();
+
 		} catch (UnpackException e) {
 			// This should be already reported to the client.
 			log(rp.getRepository(), e.getCause());