Fixes up an issue relating to U4-1010 but is only the initial fix, now need to look at the changing

the package installation process to ensure the templte files are there before the template db entries.

src/umbraco.cms/businesslogic/template/MasterpageHelper.cs

@@ -12,7 +12,13 @@ namespace umbraco.cms.businesslogic.template
     internal class MasterpageHelper
     {
         internal static readonly string DefaultMasterTemplate = SystemDirectories.Umbraco + "/masterpages/default.master";
-        internal static string CreateMasterpageFile(Template t, bool overWrite = false)
+        
+		internal static bool MasterPageExists(Template t)
+		{
+			return File.Exists(t.MasterPageFile);
+		}
+
+	    internal static string CreateMasterpageFile(Template t, bool overWrite = false)
         {
             string masterpageContent = "";
 

src/umbraco.cms/businesslogic/template/Template.cs

@@ -317,17 +317,49 @@ namespace umbraco.cms.businesslogic.template
             return DocumentType.GetAllAsList().Where(x => x.allowedTemplates.Select(t => t.Id).Contains(this.Id));
         }
 
+		/// <summary>
+		/// This checks what the default rendering engine is set in config but then also ensures that there isn't already 
+		/// a template that exists in the opposite rendering engine's template folder, then returns the appropriate 
+		/// rendering engine to use.
+		/// </summary>
+		/// <param name="t"></param>
+		/// <returns></returns>
+		/// <remarks>
+		/// The reason this is required is because for example, if you have a master page file already existing under ~/masterpages/Blah.aspx
+		/// and then you go to create a template in the tree called Blah and the default rendering engine is MVC, it will create a Blah.cshtml 
+		/// empty template in ~/Views. This means every page that is using Blah will go to MVC and render an empty page. 
+		/// This is mostly related to installing packages since packages install file templates to the file system and then create the 
+		/// templates in business logic. Without this, it could cause the wrong rendering engine to be used for a package.
+		/// </remarks>
+		private static RenderingEngine DetermineRenderingEngine(Template t)
+		{
+			var engine = Umbraco.Core.Configuration.UmbracoSettings.DefaultRenderingEngine;
+			switch (engine)
+			{
+				case RenderingEngine.Mvc:
+					//check if there's a view in ~/masterpages
+					if (MasterpageHelper.MasterPageExists(t) && !ViewHelper.ViewExists(t))
+					{
+						//change this to webforms since there's already a file there for this template alias
+						engine = RenderingEngine.WebForms;
+					}
+					break;
+				case RenderingEngine.WebForms:
+					//check if there's a view in ~/views
+					if (ViewHelper.ViewExists(t) && !MasterpageHelper.MasterPageExists(t))
+					{
+						//change this to mvc since there's already a file there for this template alias
+						engine = RenderingEngine.Mvc;
+					}
+					break;
+			}
+			return engine;
+		} 
+
         public static Template MakeNew(string Name, BusinessLogic.User u, Template master)
         {
             Template t = MakeNew(Name, u);
-            t.MasterTemplate = master.Id;
-
-            if (Umbraco.Core.Configuration.UmbracoSettings.DefaultRenderingEngine == RenderingEngine.Mvc)
-                ViewHelper.CreateViewFile(t, true);
-            else
-                MasterpageHelper.CreateMasterpageFile(t, true);
-            
-            
+            t.MasterTemplate = master.Id;			
 
             /*
             if (UmbracoSettings.UseAspNetMasterPages)
@@ -374,11 +406,15 @@ namespace umbraco.cms.businesslogic.template
             NewEventArgs e = new NewEventArgs();
             t.OnNew(e);
 
-            if (Umbraco.Core.Configuration.UmbracoSettings.DefaultRenderingEngine == RenderingEngine.Mvc)
-                t._design = ViewHelper.CreateViewFile(t);
-            else
-                t._design = MasterpageHelper.CreateMasterpageFile(t);
-
+			switch (DetermineRenderingEngine(t))
+			{
+				case RenderingEngine.Mvc:
+					ViewHelper.CreateViewFile(t, true);
+					break;
+				case RenderingEngine.WebForms:
+					MasterpageHelper.CreateMasterpageFile(t, true);
+					break;
+			}
 
             return t;
         }

src/umbraco.cms/businesslogic/template/ViewHelper.cs

@@ -9,6 +9,12 @@ namespace umbraco.cms.businesslogic.template
 {
     class ViewHelper
     {
+		internal static bool ViewExists(Template t)
+		{
+			string path = IOHelper.MapPath(ViewPath(t));
+			return File.Exists(path);
+		}
+
         internal static string GetViewFile(Template t)
         {
             string viewContent = "";