Ah, seems my top-level

BUILD

file created by

pants tailor ::

included:

python_sources(  
    name="root",
)

But no python files were in the top level dir.

What is in the top-level dir? Tailor obviously saw something there that it thought required a target, and that error indicates that something in that dir needs a source root, so...

Ah, I see! I use

pyinvoke

which places a

tasks.py

at the source root - that's probably why 👍

That would do it