Merge branch 'find_package-prefer-config-not-found' into release-3.15

Merge-request: !3653
diff --git a/Source/cmFindPackageCommand.cxx b/Source/cmFindPackageCommand.cxx
index 1d4a8ed..171fa77 100644
--- a/Source/cmFindPackageCommand.cxx
+++ b/Source/cmFindPackageCommand.cxx
@@ -507,7 +507,9 @@
         loadedPackage = true;
       } else {
         // The package was not loaded. Report errors.
-        HandlePackageMode(HandlePackageModeType::Module);
+        if (HandlePackageMode(HandlePackageModeType::Module)) {
+          loadedPackage = true;
+        }
       }
     }
   } else {
diff --git a/Tests/FindPackageTest/CMakeLists.txt b/Tests/FindPackageTest/CMakeLists.txt
index da79f5d..1b9c973 100644
--- a/Tests/FindPackageTest/CMakeLists.txt
+++ b/Tests/FindPackageTest/CMakeLists.txt
@@ -625,3 +625,9 @@
 if(ACME_FOUND)
     message(SEND_ERROR "Should not find ACME package")
 endif()
+
+############################################################################
+##Test find_package CMAKE_FIND_PACKAGE_PREFER_CONFIG with unknown package
+
+set(CMAKE_FIND_PACKAGE_PREFER_CONFIG ON)
+find_package(DoesNotExist)