Meson misdiagnoses tox venvs as being part of the source tree

[aragilar]

Describe the bug
Using tox (or any venv in the same directory as the meson.build/pyproject.toml) with meson and trying to link with any dependencies (e.g. numpy) causes the "Tried to form an absolute path to a dir in the source tree." error. Given the substantial ecosystem build around having the venv in-tree, either having the venv auto-detected and ignored (especially given this is where the files are going to be installed), or being able to mark the directory as ignored, seems like a better use of effort than trying to change the python ecosystem.

To Reproduce
Minimal example at https://github.com/aragilar/meson-tox-example

Expected behavior
tox and meson do not conflict, and build succeed in the same as if the venv was somewhere else (e.g. in the user's home directory).

system parameters

• Is this a cross build or just a plain native build (for the same computer)?
  • Native
• what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.)
  • Debian Unstable (should be independent of OS)
• what Python version are you using e.g. 3.8.0
  • 3.11, 3.12
• what meson --version
  • 1.4.1
• what ninja --version if it's a Ninja build
  • 1.12.1