I have a package that is build using flit-core (actually via flit-scm). When running flit build it follows the documentation in that it packages all git tracked files in the repository. When doing the build via python -m build it instead gathers only the files in our modules subdir though I don't really ever specified that? (that i.e. doesn't include the tests, which I'd like to ship in the sdist as well).

The [tool.flit.sdist] include and exclude directives can be used to work around that but it seems odd that I'd need a different set of directives between different build frontends.

Is this behaviour to be expected for some reason or is this a bug?