ReceivePack: Correct type of not provided object

If a tree was referenced but not provided in the pack, report it
as a missing tree and not as a missing blob.

Change-Id: Iab05705349cdf0d30cc3f8afc6698a8d2a941343
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

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

@@ -827,7 +827,7 @@ public class ReceivePack {
 				throw new MissingObjectException(o, Constants.TYPE_BLOB);
 
 			if (ensureObjectsProvidedVisible && !providedObjects.contains(o))
-				throw new MissingObjectException(o, Constants.TYPE_BLOB);
+				throw new MissingObjectException(o, o.getType());
 		}
 	}