CreateBranchCommand: Wrong existence check

Bug: 337044
Change-Id: I89224719712c1f1ab80ea34280139dfeb00be3d0
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

 		checkCallable();
 		processOptions();
 		try {
-			boolean exists = repo.getRef(name) != null;
+			Ref refToCheck = repo.getRef(name);
+			boolean exists = refToCheck != null
+					&& refToCheck.getName().startsWith(Constants.R_HEADS);
 			if (!force && exists)
 				throw new RefAlreadyExistsException(MessageFormat.format(
 						JGitText.get().refAlreadExists, name));