pass custom paths e.g. user paths to the pip subprocess

now pip list also shows packages installed to e.g. the addons folder

Author: hannesdelbeke

__init__.py

@@ -18,6 +18,7 @@
 import subprocess
 import bpy
 from pathlib import Path
+import os
 
 MODULES_FOLDER = Path(bpy.utils.user_resource("SCRIPTS")) / "modules"
 
@@ -37,6 +38,14 @@ def run_pip_command(self, *cmds, cols=False, run_module="pip"):
 
     cmds = [c for c in cmds if c is not None]
 
+    # combine all entries in os.path with path separator
+    joined_paths = os.pathsep.join(sys.path)
+    env_var = os.environ.get("PYTHONPATH")
+    if env_var:
+        os.environ["PYTHONPATH"] = f"{env_var}{os.pathsep}{joined_paths}"
+    else:
+        os.environ["PYTHONPATH"] = joined_paths
+
     # TODO: make this function only run pip commands, make separate function to run other modules
     # Choose where to save Python modules
     # if bpy.context.scene.pip_modules_home and MODULES_FOLDER.exists() and run_module == "pip":