--disable-module-dirauth has no effect

I've been trying to disable dirauth support in Alpine's tor package, but it seems that --disable-module-dirauth isn't working, as the size of the binary didn't change when the flag was added.

Am I doing something wrong? Note that the tests still mention dirauth-related things, so maybe asking the build system to build and run the testsuite makes it ignore --disable-module-dirauth?