fix(environment): update python executable lookup

This fix resolves a faulty path on MSYS2 MinGW CPython, where the bin/ segment
is missing altogether. This is required by the uninstall routine. It also
simplifies the lookup on all other platforms.

As far as I comprehended, the condition in line 255 would never be met, as the
joinpath('python') in line 254 guarantees that py will never become a
false-equivalent value, since its definition is in the else statement, hence
catches the unmatched condition in line 251.

I've also inverted the condition of checking for self._python, so that an
intermediate assignment to `py` is no longer required.

Author: ByteB4rb1e

pipenv/environment.py

@@ -26,6 +26,7 @@
 from pipenv.utils.indexes import prepare_pip_source_args
 from pipenv.utils.processes import subprocess_run
 from pipenv.utils.shell import temp_environ
+from pipenv.utils.virtualenv import virtualenv_scripts_dir
 from pipenv.vendor.importlib_metadata.compat.py39 import normalized_name
 from pipenv.vendor.pythonfinder.utils import is_in_path
 
@@ -246,16 +247,12 @@ def script_basedir(self) -> str:
     @property
     def python(self) -> str:
         """Path to the environment python"""
-        if self._python is not None:
-            return self._python
-        if os.name == "nt" and not self.is_venv:
-            py = Path(self.prefix).joinpath("python").absolute().as_posix()
-        else:
-            py = Path(self.script_basedir).joinpath("python").absolute().as_posix()
-        if not py:
-            py = Path(sys.executable).as_posix()
-        self._python = py
-        return py
+        if self._python is None:
+            self._python = (
+                (virtualenv_scripts_dir(self.prefix) / "python").absolute().as_posix()
+            )
+
+        return self._python
 
     @cached_property
     def sys_path(self) -> list[str]: