PyAPI: free internal Python data using sys.exit(..)

Previously BPY_python_end wasn't called when scripts called sys.exit()
because BPY_python_end exited the Python interpreter.

Change this behavior to call BPY_python_end without exiting the Python
interpreter while freeing Blender/Python data.

While leaks in the context of sys.exit aren't especially important
it's generally preferable for sys.exit() to match Blender's code-paths
for exiting to avoid unexpected behavior.

source/blender/python/BPY_extern_python.h

@@ -23,7 +23,7 @@ extern "C" {
 
 /** Call #BPY_context_set first. */
 void BPY_python_start(struct bContext *C, int argc, const char **argv);
-void BPY_python_end(void);
+void BPY_python_end(bool do_python_exit);
 void BPY_python_reset(struct bContext *C);
 void BPY_python_use_system_env(void);
 void BPY_python_backtrace(FILE *fp);

source/blender/python/intern/bpy_interface.cc

@@ -535,7 +535,7 @@ void BPY_python_start(bContext *C, int argc, const char **argv)
 #endif
 }
 
-void BPY_python_end()
+void BPY_python_end(const bool do_python_exit)
 {
   PyGILState_STATE gilstate;
 
@@ -564,14 +564,16 @@ void BPY_python_end()
   BPY_app_translations_end();
 
 #ifndef WITH_PYTHON_MODULE
-  /* Without this we get recursive calls to #WM_exit. */
+  /* Without this we get recursive calls to #WM_exit_ex. */
   BPY_atexit_unregister();
 
-  Py_Finalize();
-
+  if (do_python_exit) {
+    Py_Finalize();
+  }
   (void)gilstate;
 #else
   PyGILState_Release(gilstate);
+  (void)do_python_exit;
 #endif
 
 #ifdef TIME_PY_RUN

source/blender/python/intern/bpy_interface_atexit.cc

@@ -34,13 +34,13 @@ static PyObject *bpy_atexit(PyObject * /*self*/, PyObject * /*args*/, PyObject *
 
   bContext *C = BPY_context_get();
   /* As Python requested the exit, it handles shutting it's self down. */
-  const bool do_python = false;
+  const bool do_python_exit = false;
   /* User actions such as saving the session, preferences, recent-files for e.g.
    * should be skipped because an explicit call to exit is more likely to be used as part of
    * automated processes shouldn't impact the users session in the future. */
   const bool do_user_exit_actions = false;
 
-  WM_exit_ex(C, do_python, do_user_exit_actions);
+  WM_exit_ex(C, do_python_exit, do_user_exit_actions);
 
   Py_RETURN_NONE;
 }

source/blender/windowmanager/WM_api.hh

@@ -109,15 +109,14 @@ void WM_init(bContext *C, int argc, const char **argv);
  *
  * \param C: The context or null, a null context implies `do_user_exit_actions == false` &
  * prevents some editor-exit operations from running.
- * \param do_python: Free all data associated with Blender's Python integration.
- * Also exit the Python interpreter (unless `WITH_PYTHON_MODULE` is enabled).
+ * \param do_python_exit: Exit the Python interpreter (unless `WITH_PYTHON_MODULE` is enabled).
  * \param do_user_exit_actions: When enabled perform actions associated with a user
  * having been using Blender then exiting. Actions such as writing the auto-save
  * and writing any changes to preferences.
  * Set to false in background mode or when exiting because of failed command line argument parsing.
  * In general automated actions where the user isn't making changes should pass in false too.
  */
-void WM_exit_ex(bContext *C, bool do_python, bool do_user_exit_actions);
+void WM_exit_ex(bContext *C, bool do_python_exit, bool do_user_exit_actions);
 
 /**
  * Main exit function to close Blender ordinarily.

source/blender/windowmanager/intern/wm_init_exit.cc

@@ -490,7 +490,7 @@ void wm_exit_schedule_delayed(const bContext *C)
 
 void UV_clipboard_free();
 
-void WM_exit_ex(bContext *C, const bool do_python, const bool do_user_exit_actions)
+void WM_exit_ex(bContext *C, const bool do_python_exit, const bool do_user_exit_actions)
 {
   wmWindowManager *wm = C ? CTX_wm_manager(C) : nullptr;
 
@@ -663,8 +663,8 @@ void WM_exit_ex(bContext *C, const bool do_python, const bool do_user_exit_actio
   //  free_txt_data();
 
 #ifdef WITH_PYTHON
-  /* option not to close python so we can use 'atexit' */
-  if (do_python && ((C == nullptr) || CTX_py_init_get(C))) {
+  /* Option not to exit Python so this function can called from 'atexit'. */
+  if ((C == nullptr) || CTX_py_init_get(C)) {
     /* NOTE: (old note)
      * before BKE_blender_free so Python's garbage-collection happens while library still exists.
      * Needed at least for a rare crash that can happen in python-drivers.
@@ -672,7 +672,7 @@ void WM_exit_ex(bContext *C, const bool do_python, const bool do_user_exit_actio
      * Update for Blender 2.5, move after #BKE_blender_free because Blender now holds references
      * to #PyObject's so #Py_DECREF'ing them after Python ends causes bad problems every time
      * the python-driver bug can be fixed if it happens again we can deal with it then. */
-    BPY_python_end();
+    BPY_python_end(do_python_exit);
   }
 #else
   (void)do_python;