Document empty catch block to silence warning

Change-Id: I643f916e394ca95272b58d0b5826e81cc1092f2f
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -246,6 +246,7 @@ public class ReceivePack extends BaseReceivePack {
 				try {
 					postReceive.onPostReceive(this, filterCommands(Result.OK));
 				} catch (Throwable e) {
+					// empty
 				}
 				throw new UnpackException(unpackError);
 			}