Check for refs/ not refs/heads/ when updating a ref

Change-Id: I19f9507fdb859902a6df96f1960433a91378e400
diff --git a/src/main/java/com/gitblit/utils/JGitUtils.java b/src/main/java/com/gitblit/utils/JGitUtils.java
index 75a4405..ecc6359 100644
--- a/src/main/java/com/gitblit/utils/JGitUtils.java
+++ b/src/main/java/com/gitblit/utils/JGitUtils.java
@@ -1540,7 +1540,7 @@
 	 */

 	public static boolean setBranchRef(Repository repository, String branch, String commitId) {

 		String branchName = branch;

-		if (!branchName.startsWith(Constants.R_HEADS)) {

+		if (!branchName.startsWith(Constants.R_REFS)) {

 			branchName = Constants.R_HEADS + branch;

 		}