gh-140141: Properly break exception chain in importlib.metadata.Distribution.from_name (#140142)

Author: bswck

Lib/importlib/metadata/__init__.py

@@ -457,7 +457,7 @@ def from_name(cls, name: str) -> Distribution:
         try:
             return next(iter(cls._prefer_valid(cls.discover(name=name))))
         except StopIteration:
-            raise PackageNotFoundError(name)
+            raise PackageNotFoundError(name) from None
 
     @classmethod
     def discover(

Misc/NEWS.d/next/Library/2025-10-15-17-23-51.gh-issue-140141.j2mUDB.rst

@@ -0,0 +1,5 @@
+The :py:class:`importlib.metadata.PackageNotFoundError` traceback raised when
+``importlib.metadata.Distribution.from_name`` cannot discover a
+distribution no longer includes a transient :exc:`StopIteration` exception trace.
+
+Contributed by Bartosz Sławecki in :gh:`140142`.