After upgrade to go1.13, some of my projects build failed, with message

Error determining list of magefiles: failed to list non-mage gofiles: exit status 1
exit status 1

And clone mage repository, check out master branch, run go test -race ./... failed too.

go list files cause error if all files has build constraints. For example, cd mage/testdata/no_default, then run go list -f '{{join .GoFiles "||"}}', error occurs with message

build .: cannot find module for path .