Revert "Use functools.lru_cache to cache extension point discovery"

This reverts commit 1b85894.

colcon_core/extension_point.py

@@ -3,7 +3,6 @@
 # Licensed under the Apache License, Version 2.0
 
 from collections import defaultdict
-from functools import lru_cache
 import os
 import traceback
 
@@ -47,7 +46,6 @@ def _get_unique_distributions():
             yield dist
 
 
-@lru_cache()
 def get_all_extension_points():
     """
     Get all extension points related to `colcon` and any of its extensions.
@@ -80,7 +78,6 @@ def get_all_extension_points():
     return entry_points
 
 
-@lru_cache()
 def get_extension_points(group):
     """
     Get the extension points for a specific group.
@@ -139,7 +136,6 @@ def load_extension_points(group, *, excludes=None):
     return extension_types
 
 
-@lru_cache()
 def load_extension_point(name, value, group):
     """
     Load the extension point.

test/test_extension_point.py

@@ -101,7 +101,6 @@ def test_extension_point_blocklist():
 
         # successful loading of entry point not in blocklist
         load.reset_mock()
-        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST=os.pathsep.join([
             'group1.extB', 'group2.extC'])
         ):
@@ -110,7 +109,6 @@ def test_extension_point_blocklist():
 
         # entry point in a blocked group can't be loaded
         load.reset_mock()
-        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST='group1'):
             with pytest.raises(RuntimeError) as e:
                 load_extension_point('extA', 'eA', 'group1')
@@ -119,7 +117,6 @@ def test_extension_point_blocklist():
         assert load.call_count == 0
 
         # entry point listed in the blocklist can't be loaded
-        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST=os.pathsep.join([
             'group1.extA', 'group1.extB'])
         ):