Don't copy the environment to update it

This causes problems on windows, and is wasteful anyway. The subprocess
will pick up the environment from its parent.

support/test/python/simple_python/.vimspector.json

@@ -1,8 +1,12 @@
 {
   "$schema": "https://puremourning.github.io/vimspector/schema/vimspector.schema.json",
   "adapters": {
-    "test_custom": {
-      "command": "This is a test"
+    "run_with_debugpy": {
+      "command": [ "${workspaceRoot}/run_with_debugpy" ],
+      "port": 9876,
+      "env": {
+        "DEBUG_PORT": "9876"
+      }
     }
   },
   "configurations": {
@@ -44,6 +48,19 @@
         }
       }
     },
+    "attach-run": {
+      "adapter": "run_with_debugpy",
+      "configuration": {
+        "request": "attach"
+      },
+      "breakpoints": {
+        "exception": {
+          "raised": "N",
+          "uncaught": "",
+          "userUnhandled": ""
+        }
+      }
+    },
     "run": {
       "adapter": "debugpy",
       "configuration": {

support/test/python/simple_python/run_with_debugpy

@@ -1,9 +1,7 @@
 #!/usr/bin/env bash
 
-PYTHON=python3
-
-if [ -n "$1" ]; then
-  PYTHON=$1
+if [ -z "$DEBUG_PORT" ]; then
+  DEBUG_PORT=5678
 fi
 
 pushd $(dirname $0)
@@ -11,10 +9,11 @@ pushd $(dirname $0)
     rm -rf env
   fi
 
-  $PYTHON -m venv env
+  python3 -m venv env
   . env/bin/activate
   python -m pip install -r requirements.txt
+  echo "using port $DEBUG_PORT"
   echo "*** Launching ***"
-  python -m debugpy --wait-for-client --listen 0.0.0.0:5678 main.py
+  python -m debugpy --wait-for-client --listen 0.0.0.0:${DEBUG_PORT} main.py
 popd