Sync script changes from the runtime repo (#19062)

* Sync script changes from the runtime repo #18943

* Additional change

Author: Tratcher

src/Shared/runtime/CopyToAspNetCore.cmd

@@ -10,5 +10,6 @@ IF [%remote_repo%] == [] (
 
 echo ASPNETCORE_REPO: %remote_repo%
 
-robocopy . %remote_repo%\src\Shared\runtime /MIR
-robocopy .\..\..\..\..\..\tests\Tests\System\Net\aspnetcore\ %remote_repo%\src\Shared\test\Shared.Tests\runtime /MIR
+REM https://superuser.com/questions/280425/getting-robocopy-to-return-a-proper-exit-code
+(robocopy . %remote_repo%\src\Shared\runtime /MIR) ^& IF %ERRORLEVEL% LSS 8 SET ERRORLEVEL = 0
+(robocopy .\..\..\..\..\..\tests\Tests\System\Net\aspnetcore\ %remote_repo%\src\Shared\test\Shared.Tests\runtime /MIR) ^& IF %ERRORLEVEL% LSS 8 SET ERRORLEVEL = 0

src/Shared/runtime/CopyToRuntime.cmd

@@ -10,5 +10,6 @@ IF [%remote_repo%] == [] (
 
 echo RUNTIME_REPO: %remote_repo%
 
-robocopy . %remote_repo%\src\libraries\Common\src\System\Net\Http\aspnetcore /MIR
-robocopy .\..\test\Shared.Tests\runtime %remote_repo%\src\libraries\Common\tests\Tests\System\Net\aspnetcore /MIR
+REM https://superuser.com/questions/280425/getting-robocopy-to-return-a-proper-exit-code
+(robocopy . %remote_repo%\src\libraries\Common\src\System\Net\Http\aspnetcore /MIR) ^& IF %ERRORLEVEL% LSS 8 SET ERRORLEVEL = 0
+(robocopy .\..\test\Shared.Tests\runtime %remote_repo%\src\libraries\Common\tests\Tests\System\Net\aspnetcore /MIR) ^& IF %ERRORLEVEL% LSS 8 SET ERRORLEVEL = 0

src/Shared/runtime/Http3/QPack/QPackDecoder.cs

@@ -224,7 +224,7 @@ private void OnByte(byte b, IHttpHeadersHandler handler)
                     }
                     break;
                 case State.CompressedHeaders:
-                    switch (BitOperations.LeadingZeroCount(b) - 24)
+                    switch (BitOperations.LeadingZeroCount(b) - 24) // byte 'b' is extended to uint, so will have 24 extra 0s.
                     {
                         case 0: // Indexed Header Field
                             prefixInt = IndexedHeaderFieldPrefixMask & b;