#18890: Handle empty content identity encoding

Work Item: 18890

--HG--
branch : 1.x

src/Orchard/ContentManagement/ContentIdentity.cs

@@ -47,6 +47,10 @@ namespace Orchard.ContentManagement {
         }
 
         private static string EncodeIdentityValue(string identityValue) {
+            if(String.IsNullOrEmpty(identityValue)) {
+                return "";
+            }
+
             var stringBuilder = new StringBuilder();
             foreach (var ch in identityValue.ToCharArray()) {
                 switch (ch) {