Merge changes I7b6d7be4,I63a74651,I39c2ea6b

* changes:
  Silence unused object warning in MyersDiff
  Silence resource leak warnings where caller is responsible to close
  Fix potential null pointer access in IndexDiffFilter

org.eclipse.jgit/src/org/eclipse/jgit/diff/MyersDiff.java

@@ -114,6 +114,7 @@ import org.eclipse.jgit.util.LongList;
 public class MyersDiff<S extends Sequence> {
 	/** Singleton instance of MyersDiff. */
 	public static final DiffAlgorithm INSTANCE = new LowLevelDiffAlgorithm() {
+		@SuppressWarnings("unused")
 		@Override
 		public <S extends Sequence> void diffNonCommon(EditList edits,
 				HashedSequenceComparator<S> cmp, HashedSequence<S> a,

org.eclipse.jgit/src/org/eclipse/jgit/lib/BaseRepositoryBuilder.java

@@ -565,14 +565,16 @@ public class BaseRepositoryBuilder<B extends BaseRepositoryBuilder, R extends Re
 	 * based on other options. If insufficient information is available, an
 	 * exception is thrown to the caller.
 	 *
-	 * @return a repository matching this configuration.
+	 * @return a repository matching this configuration. The caller is
+	 *         responsible to close the repository instance when it is no longer
+	 *         needed.
 	 * @throws IllegalArgumentException
 	 *             insufficient parameters were set.
 	 * @throws IOException
 	 *             the repository could not be accessed to configure the rest of
 	 *             the builder's parameters.
 	 */
-	@SuppressWarnings("unchecked")
+	@SuppressWarnings({ "unchecked", "resource" })
 	public R build() throws IOException {
 		R repo = (R) new FileRepository(setup());
 		if (isMustExist() && !repo.getObjectDatabase().exists())

org.eclipse.jgit/src/org/eclipse/jgit/lib/RepositoryCache.java

@@ -159,6 +159,7 @@ public class RepositoryCache {
 			openLocks[i] = new Lock();
 	}
 
+	@SuppressWarnings("resource")
 	private Repository openRepository(final Key location,
 			final boolean mustExist) throws IOException {
 		Reference<Repository> ref = cacheMap.get(location);

org.eclipse.jgit/src/org/eclipse/jgit/treewalk/filter/IndexDiffFilter.java

@@ -224,7 +224,8 @@ public class IndexDiffFilter extends TreeFilter {
 		// Only one chance left to detect a diff: between index and working
 		// tree. Make use of the WorkingTreeIterator#isModified() method to
 		// avoid computing SHA1 on filesystem content if not really needed.
-		return wi.isModified(di.getDirCacheEntry(), true, tw.getObjectReader());
+		return wi.isModified(di == null ? null : di.getDirCacheEntry(), true,
+				tw.getObjectReader());
 	}
 
 	/**