Errors when using the editables backend with the includes field

[xulongwu4]

I have the following sample project.

$ tree .
.
├── pyproject.toml
└── src
    ├── mypackage1
    │   └── __init__.py
    └── mypackage2
        └── __init__.py

and the content of pyproject.toml is

[project]
name = "test"
version = "0.1.0"
description = "Default template for PDM package"
authors = []
dependencies = []
requires-python = "==3.12.*"

[build-system]
requires = ["pdm-backend"]
build-backend = "pdm.backend"

[tool.pdm.build]
package-dir = "src"
includes = ["src/mypackage1", "src/mypackage2"]
editable-backend = "editables"

I only put folders inside the package-dir into includes .

However, when I ran pdm install, which would perform an editable installation of the project using editables as the backend, I got the following error message:

$ pdm install
WARNING: Lockfile does not exist
Updating the lock file...
🔒 Lock successful
Changes are written to pdm.lock.
All packages are synced to date, nothing to do.
Installing the project as an editable package...
  ✖ Install test 0.1.0 failed

See /home/oulongwu/.local/state/pdm/log/pdm-install-1abiz06e.log for detailed debug log.
[BuildError]: Build backend raised error: Showing the last 10 lines of the build output:
  File "/tmp/pdm-build-env-ik5scq67-shared/lib/python3.12/site-packages/pdm/backend/base.py", line 149, in call_hook
    getattr(hook, hook_name)(context, *args, **kwargs)
  File "/tmp/pdm-build-env-ik5scq67-shared/lib/python3.12/site-packages/pdm/backend/editable.py", line 22, in pdm_build_initialize
    editables = self._prepare_editable(context)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/pdm-build-env-ik5scq67-shared/lib/python3.12/site-packages/pdm/backend/editable.py", line 61, in _prepare_editable
    editables.map(package, os.path.join(package_dir, package))
  File "/tmp/pdm-build-env-34ob9dw_-overlay/lib/python3.12/site-packages/editables/__init__.py", line 60, in map
    raise EditableException(f"{target} is not a valid Python package or module")
editables.EditableException: src/src/mypackage1 is not a valid Python package or module
WARNING: Add '-v' to see the detailed traceback

The error happens when pdm-backend thought we are referring to src/src/mypackage1 in the call to editable.map. This is the result of calling os.path.join(package_dir, package) with package_dir set to src and package set to src/mypackage1.