DirCacheCheckout: create only one ObjectReader

This deprecated method accidentally creates two ObjectReader
instances. Use the instance created one line above that is
correctly released in the finally block.

Change-Id: Ic57d041674611802a9384d8fa1d292e821055019

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java

@@ -1170,7 +1170,7 @@ public class DirCacheCheckout {
 			DirCacheEntry entry) throws IOException {
 		ObjectReader or = repository.newObjectReader();
 		try {
-			checkoutEntry(repository, f, entry, repository.newObjectReader());
+			checkoutEntry(repository, f, entry, or);
 		} finally {
 			or.release();
 		}