Huh, for some reason the Rietveld diff missed the changes to _testmultiphase.c that are in the patch file. The change looks good to me. The test adds a new "test.imp_dummy" module, imports that, and then ensures it can be replaced by using imp.load_dynamic to import "test.imp_dummy" from the _testmultiphase module instead. The functional change itself is isolated to imp.load_dynamic, so no other code paths will be affected.