[BUG]: The main repository and submodule both have source code dependencies on the usage of pybind11

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What version (or hash if on master) of pybind11 are you using?

stable branches

Problem description

Reproduce by files uploading

Problem

When the main repo and the submodule repo also depends the pybind11 in source code way, the command pybind11_add_module in cmakelists.txt of main repo will

• use the function defined in test_pybind11/third-party/sub/third-party/pybind11/tools/pybind11Tools.cmake
• not the expected definition in test_pybind11/third-party/pybind11/tools/pybind11Tools.cmake

How to proof this problem is exist?

I have deleted this two files the pybind11 in test_pybind11/third-party/pybind11:

deleted:    tools/pybind11NewTools.cmake
deleted:    tools/pybind11Tools.cmake

But I still can build the repo successfully by

mkdir build
cd build
cmake ..
make

Reproducible example code

code is here: https://github.com/HRXWEB/test_pybind11

Is this a regression? Put the last known working version here if it is.

Not a regression

Start with the linked test_pybind11 repository and inspect its main CMakeLists.txt plus test_pybind11/third-party/pybind11/tools/pybind11Tools.cmake and the nested submodule copy. Reproduce from a clean build with cmake .. and make, then verify which pybind11_add_module definition is selected after the main copy's tool files are removed.