DescribeCommand: Refactor to not use deprecated Repository#peel

Change-Id: I76073ad62d1bc4fc21d8a1f5fc7eb92060a73baa
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
index 7f1ed8c..dc605a9 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
@@ -224,12 +224,16 @@ private Optional<Ref> getBestMatch(List<Ref> tags) {
 		}
 	}
 
-	private ObjectId getObjectIdFromRef(Ref r) {
-		ObjectId key = repo.peel(r).getPeeledObjectId();
-		if (key == null) {
-			key = r.getObjectId();
+	private ObjectId getObjectIdFromRef(Ref r) throws JGitInternalException {
+		try {
+			ObjectId key = repo.getRefDatabase().peel(r).getPeeledObjectId();
+			if (key == null) {
+				key = r.getObjectId();
+			}
+			return key;
+		} catch (IOException e) {
+			throw new JGitInternalException(e.getMessage(), e);
 		}
-		return key;
 	}
 
 	/**