Handle short branch/tag name for setBranch in CloneCommand

Before, it was not clear from the documentation what kind of branch name
was accepted. Users specifying "branch" (instead of "refs/heads/branch")
got no error message and ended up with a repository without HEAD and no
checkout.

With this, CloneCommand now tries "$branch", then "refs/heads/$branch"
and then "refs/tags/$branch". C Git only does the last two, but for
compatibility we should still allow "refs/heads/branch".

Bug: 390994
Change-Id: I4be13144f2a21a6583e0942f0c7c40da32f2247a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/CloneCommandTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011, Chris Aniszczyk <caniszczyk@gmail.com>
+ * Copyright (C) 2011, 2013 Chris Aniszczyk <caniszczyk@gmail.com>
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
@@ -64,7 +64,6 @@
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
-import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevBlob;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -92,11 +91,10 @@ public void setUp() throws Exception {
 		writeTrashFile("Test.txt", "Hello world");
 		git.add().addFilepattern("Test.txt").call();
 		git.commit().setMessage("Initial commit").call();
+		git.tag().setName("tag-initial").setMessage("Tag initial").call();
 
-		// create a master branch and switch to it
+		// create a test branch and switch to it
-		git.branchCreate().setName("test").call();
+		git.checkout().setCreateBranch(true).setName("test").call();
-		RefUpdate rup = db.updateRef(Constants.HEAD);
-		rup.link("refs/heads/test");
 
 		// commit something on the test branch
 		writeTrashFile("Test.txt", "Some change");
@@ -205,6 +203,36 @@ public void testCloneRepositoryWithBranch() throws IOException,
 				.branchList().setListMode(ListMode.ALL).call()));
 	}
 
+	@Test
+	public void testCloneRepositoryWithBranchShortName() throws Exception {
+		File directory = createTempDirectory("testCloneRepositoryWithBranch");
+		CloneCommand command = Git.cloneRepository();
+		command.setBranch("test");
+		command.setDirectory(directory);
+		command.setURI("file://" + git.getRepository().getWorkTree().getPath());
+		Git git2 = command.call();
+		addRepoToClose(git2.getRepository());
+
+		assertNotNull(git2);
+		assertEquals("refs/heads/test", git2.getRepository().getFullBranch());
+	}
+
+	@Test
+	public void testCloneRepositoryWithTagName() throws Exception {
+		File directory = createTempDirectory("testCloneRepositoryWithBranch");
+		CloneCommand command = Git.cloneRepository();
+		command.setBranch("tag-initial");
+		command.setDirectory(directory);
+		command.setURI("file://" + git.getRepository().getWorkTree().getPath());
+		Git git2 = command.call();
+		addRepoToClose(git2.getRepository());
+
+		assertNotNull(git2);
+		ObjectId taggedCommit = db.resolve("tag-initial^{commit}");
+		assertEquals(taggedCommit.name(), git2
+				.getRepository().getFullBranch());
+	}
+
 	@Test
 	public void testCloneRepositoryOnlyOneBranch() throws IOException,
 			JGitInternalException, GitAPIException {

org.eclipse.jgit/src/org/eclipse/jgit/api/CloneCommand.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011, Chris Aniszczyk <caniszczyk@gmail.com>
+ * Copyright (C) 2011, 2013 Chris Aniszczyk <caniszczyk@gmail.com>
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
@@ -198,12 +198,19 @@ private void checkout(Repository clonedRepo, FetchResult result)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException, GitAPIException {
 
-		Ref head = result.getAdvertisedRef(branch);
+		Ref head = null;
 		if (branch.equals(Constants.HEAD)) {
 			Ref foundBranch = findBranchToCheckout(result);
 			if (foundBranch != null)
 				head = foundBranch;
 		}
+		if (head == null) {
+			head = result.getAdvertisedRef(branch);
+			if (head == null)
+				head = result.getAdvertisedRef(Constants.R_HEADS + branch);
+			if (head == null)
+				head = result.getAdvertisedRef(Constants.R_TAGS + branch);
+		}
 
 		if (head == null || head.getObjectId() == null)
 			return; // throw exception?
@@ -362,7 +369,9 @@ public CloneCommand setRemote(String remote) {
 
 	/**
 	 * @param branch
-	 *            the initial branch to check out when cloning the repository
+	 *            the initial branch to check out when cloning the repository.
+	 *            Can be specified as ref name (<code>refs/heads/master</code>),
+	 *            branch name (<code>master</code>) or tag name (<code>v1.2.3</code>).
 	 * @return this instance
 	 */
 	public CloneCommand setBranch(String branch) {
@@ -409,7 +418,8 @@ public CloneCommand setCloneSubmodules(boolean cloneSubmodules) {
 	/**
 	 * @param branchesToClone
 	 *            collection of branches to clone. Ignored when allSelected is
-	 *            true.
+	 *            true. Must be specified as full ref names (e.g.
+	 *            <code>refs/heads/master</code>).
 	 * @return {@code this}
 	 */
 	public CloneCommand setBranchesToClone(Collection<String> branchesToClone) {