Reverts how UmbracoContextReference works

src/Umbraco.Abstractions/UmbracoContextReference.cs

@@ -14,22 +14,24 @@ namespace Umbraco.Web
     /// </remarks>
     public class UmbracoContextReference : IDisposable //fixme - should we inherit from DisposableObjectSlim?
     {
+        private readonly IUmbracoContextAccessor _umbracoContextAccessor;
         private bool _disposed;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="UmbracoContextReference"/> class.
         /// </summary>
-        internal UmbracoContextReference(bool isRoot, IUmbracoContext umbracoContext)
+        internal UmbracoContextReference(IUmbracoContext umbracoContext, bool isRoot, IUmbracoContextAccessor umbracoContextAccessor)
         {
             IsRoot = isRoot;
 
             UmbracoContext = umbracoContext;
+            _umbracoContextAccessor = umbracoContextAccessor;
         }
 
         /// <summary>
         /// Gets the <see cref="UmbracoContext"/>.
         /// </summary>
-        public IUmbracoContext UmbracoContext { get; private set; }
+        public IUmbracoContext UmbracoContext { get; }
 
         /// <summary>
         /// Gets a value indicating whether the reference is a root reference.
@@ -49,7 +51,7 @@ namespace Umbraco.Web
             if (IsRoot)
             {
                 UmbracoContext.Dispose();
-                UmbracoContext = null;
+                _umbracoContextAccessor.UmbracoContext = null;
             }
 
             GC.SuppressFinalize(this);

src/Umbraco.Web/UmbracoContextFactory.cs

@@ -77,13 +77,13 @@ namespace Umbraco.Web
         {
             var currentUmbracoContext = _umbracoContextAccessor.UmbracoContext;
             if (currentUmbracoContext != null)
-                return new UmbracoContextReference(false, currentUmbracoContext);
+                return new UmbracoContextReference(currentUmbracoContext, false, _umbracoContextAccessor);
 
 
             var umbracoContext = CreateUmbracoContext();
             _umbracoContextAccessor.UmbracoContext = umbracoContext;
 
-            return new UmbracoContextReference(true, umbracoContext);
+            return new UmbracoContextReference(umbracoContext, true, _umbracoContextAccessor);
         }
 
         // dummy TextWriter that does not write