Correct keyed-service probing for built-in DI services

src/libraries/Microsoft.Extensions.DependencyInjection.Specification.Tests/src/ServiceProviderIsKeyedServiceSpecificationTests.cs

@@ -125,5 +125,30 @@ public void NonKeyedServiceWithIsKeyedService()
             Assert.NotNull(serviceProviderIsService);
             Assert.True(serviceProviderIsService.IsKeyedService(typeof(IFakeService), null));
         }
+
+        [Theory]
+        [InlineData(typeof(IServiceProvider))]
+        [InlineData(typeof(IServiceScopeFactory))]
+        [InlineData(typeof(IServiceProviderIsService))]
+        [InlineData(typeof(IServiceProviderIsKeyedService))]
+        public void BuiltInServicesWithIsKeyedServiceOnlyReturnTrueForNullServiceKey(Type builtInServiceType)
+        {
+            if (!SupportsIServiceProviderIsKeyedService)
+            {
+                return;
+            }
+
+            // Arrange
+            var provider = CreateServiceProvider(new TestServiceCollection());
+
+            // Act
+            var serviceProviderIsService = provider.GetService<IServiceProviderIsKeyedService>();
+
+            // Assert
+            Assert.NotNull(serviceProviderIsService);
+            Assert.True(serviceProviderIsService.IsKeyedService(builtInServiceType, null));
+            Assert.False(serviceProviderIsService.IsKeyedService(builtInServiceType, new object()));
+            Assert.False(serviceProviderIsService.IsKeyedService(builtInServiceType, KeyedService.AnyKey));
+        }
     }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteFactory.cs

@@ -814,10 +814,11 @@ internal bool IsService(ServiceIdentifier serviceIdentifier)
 
             // These are the built in service types that aren't part of the list of service descriptors
             // If you update these make sure to also update the code in ServiceProvider.ctor
-            return serviceType == typeof(IServiceProvider) ||
-                   serviceType == typeof(IServiceScopeFactory) ||
-                   serviceType == typeof(IServiceProviderIsService) ||
-                   serviceType == typeof(IServiceProviderIsKeyedService);
+            return serviceIdentifier.ServiceKey is null &&
+                   (serviceType == typeof(IServiceProvider) ||
+                    serviceType == typeof(IServiceScopeFactory) ||
+                    serviceType == typeof(IServiceProviderIsService) ||
+                    serviceType == typeof(IServiceProviderIsKeyedService));
         }
 
         private struct ServiceDescriptorCacheItem