Fix disabled code coverage for src folder. (#2259)

* fix disabled code coverage for src folder.

* add comment.

Author: codemzs

test/Directory.Build.props

@@ -6,8 +6,6 @@
     <TargetFramework Condition="$(Configuration.EndsWith('-netfx'))">net461</TargetFramework>
     <TargetFramework Condition="'$(UseIntrinsics)' == 'true'">netcoreapp3.0</TargetFramework>
     <RuntimeIdentifier Condition="'$(TargetFramework)' == 'net461'">win-x64</RuntimeIdentifier>
-    <!-- This is required in order to have following extension files in the output folder of the projects referencing other projects. -->
-    <AllowedReferenceRelatedFileExtensions>$(AllowedReferenceRelatedFileExtensions);.runtimeconfig.json;.runtimeconfig.dev.json;.deps.json</AllowedReferenceRelatedFileExtensions>  
     <IsPackable>false</IsPackable>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
 

test/Directory.Build.targets

@@ -2,6 +2,12 @@
 
   <Import Project="..\Directory.Build.targets" />
 
+  <PropertyGroup>
+    <!-- This needs to be in Directory.Build.targets or the default value for AllowedReferenceRelatedFileExtensions will not be applied. 
+         This is required in order to have following extension files in the output folder of the projects referencing other projects. -->
+    <AllowedReferenceRelatedFileExtensions>$(AllowedReferenceRelatedFileExtensions);.runtimeconfig.json;.runtimeconfig.dev.json;.deps.json</AllowedReferenceRelatedFileExtensions>  
+  </PropertyGroup>
+
   <!-- Workaround for https://github.com/tonerdo/coverlet/pull/318 -->
   <Target Name="UpdateTargetPathForCoverage" BeforeTargets="InstrumentModulesNoBuild;InstrumentModulesAfterBuild">
     <PropertyGroup>