sdist build fails when artifacts from different versions are present

I was developing on some Beam branch, then I switched git branches to a different branch. These two branches had different python_sdk_version properties set [1], say version A and version B. When I run Gradle task :sdks:python:sdist, it will fail with error:

Expected directory ... to contain exactly one file, however, it contains more than one file.

This happens because the tarball labeled version A is still present, along with the new tarball for version B. I can get around this by cleaning the build directory, but this is an extra step and is not immediately obvious. It would be better if it just worked.

[1] https://github.com/ibzib/beam/blob/default-region/gradle.properties#L27