disable building Microsoft.AspNetCore.App.Ref package in 3.0

src/Framework/ref/Microsoft.AspNetCore.App.Ref.csproj

@@ -85,7 +85,7 @@ This package is an internal implementation of the .NET Core SDK and is not meant
     </BuildDependsOn>
 
     <!-- No-op when in source build -->
-    <BuildDependsOn Condition="'$(IsTargetingPackBuilding)' != 'false' and '$(DotNetBuildFromSource)' == 'true'"/>
+    <BuildDependsOn Condition="'$(IsTargetingPackBuilding)' != 'false' or '$(DotNetBuildFromSource)' == 'true'"/>
   </PropertyGroup>
 
   <!-- Override the default MSBuild targets so that nothing is returned from the project since it represents a collection of assemblies. -->