[IMP] snippets: preserve same file module

In `make_pickleable_callback`, when creating a name for the module created via
import_script, no longer make the name random, but derive it from the script's
path deterministically via a hash function. This way, when this method is
called multiple times from the same script for multiple callbacks, it will only
import the script once and otherwise re-use the created module. This ensures
multiple callbacks from the same script file will run within the same module,
seeing e.g. the same values in modified globals, which is much more intuitive.

Author: cawo-odoo

src/util/snippets.py

@@ -1,9 +1,9 @@
 # -*- coding: utf-8 -*-
+import hashlib
 import inspect
 import logging
 import re
 import sys
-import uuid
 from concurrent.futures import ProcessPoolExecutor
 
 from lxml import etree, html
@@ -171,10 +171,11 @@ def make_pickleable_callback(callback):
     We should then put the executed function in its own importable file.
     """
     callback_filepath = inspect.getfile(callback)
-    name = f"_upgrade_{uuid.uuid4().hex}"
-    mod = sys.modules[name] = import_script(callback_filepath, name=name)
+    name = f"_upgrade_{hashlib.sha256(callback_filepath.encode()).hexdigest()}"
+    if name not in sys.modules:
+        sys.modules[name] = import_script(callback_filepath, name=name)
     try:
-        return getattr(mod, callback.__name__)
+        return getattr(sys.modules[name], callback.__name__)
     except AttributeError:
         error_msg = (
             f"The converter callback `{callback.__name__}` is a nested function in `{callback.__module__}`.\n"