Peel tags during resolve of foo^

Once we start talking about parents of tags, we are in the commit
graph, so treat all objects from this point as commits. This fixes
spurious IncorrectObjectTypeExceptions on resolving expressions like
tag^^.

Change-Id: I29ece1fdb49c9c5b9ca415efcd1876bc72e97120

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RepositoryResolveTest.java

@@ -178,9 +178,11 @@ public class RepositoryResolveTest extends SampleDataRepositoryTestCase {
 		assertEquals("d86a2aada2f5e7ccf6f11880bfb9ab404e8a8864",db.resolve("refs/tags/B10th^0").name());
 		assertEquals("d86a2aada2f5e7ccf6f11880bfb9ab404e8a8864",db.resolve("refs/tags/B10th~0").name());
 		assertEquals("0966a434eb1a025db6b71485ab63a3bfbea520b6",db.resolve("refs/tags/B10th^").name());
+		assertEquals("2c349335b7f797072cf729c4f3bb0914ecb6dec9",db.resolve("refs/tags/B10th^^").name());
 		assertEquals("0966a434eb1a025db6b71485ab63a3bfbea520b6",db.resolve("refs/tags/B10th^1").name());
 		assertEquals("0966a434eb1a025db6b71485ab63a3bfbea520b6",db.resolve("refs/tags/B10th~1").name());
 		assertEquals("2c349335b7f797072cf729c4f3bb0914ecb6dec9",db.resolve("refs/tags/B10th~2").name());
+		assertEquals("2c349335b7f797072cf729c4f3bb0914ecb6dec9",db.resolve("refs/tags/B10th^~1").name());
 	}
 
 	@Test

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

@@ -509,7 +509,7 @@ public abstract class Repository {
 						done = k;
 						break;
 					default:
-						rev = rw.parseAny(rev);
+						rev = rw.peel(rev);
 						if (rev instanceof RevCommit) {
 							RevCommit commit = ((RevCommit) rev);
 							if (commit.getParentCount() == 0)