Don't add discovered extra path if it's a source path

We don't want to have duplicated paths between extra and source paths
either, otherwise things will be processed twice.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -52,6 +52,8 @@
 
 - The distribution package doesn't include tests and other useless files anymore.
 
+- nox: When discovering path *extra paths*, now paths will not be added if they are also *source paths*, as we don't want any duplicates.
+
 ### Cookiecutter template
 
 - Now the CI workflow will checkout the submodules.

src/frequenz/repo/config/nox/config.py

@@ -92,7 +92,7 @@ def __post_init__(self) -> None:
         This will add extra paths discovered in config files and other sources.
         """
         for path in _util.discover_paths():
-            if path not in self.extra_paths:
+            if path not in self.extra_paths and path not in self.source_paths:
                 self.extra_paths.append(path)
 
     def copy(self, /) -> Self: