Adjust for variable stacklevel on partial calls in PyPy. Fixes #327.

CHANGES.rst

@@ -1,3 +1,9 @@
+v4.6.1
+======
+
+* #327: Deprecation warnings now honor call stack variance
+  on PyPy.
+
 v4.6.0
 ======
 

importlib_metadata/__init__.py

@@ -7,6 +7,7 @@
 import email
 import pathlib
 import operator
+import platform
 import textwrap
 import warnings
 import functools
@@ -48,6 +49,16 @@
 ]
 
 
+def _pypy_partial(val):
+    """
+    Adjust for variable stacklevel on partial under PyPy.
+
+    Workaround for #327.
+    """
+    is_pypy = platform.python_implementation() == 'PyPy'
+    return val + is_pypy
+
+
 class PackageNotFoundError(ModuleNotFoundError):
     """The package was not found."""
 
@@ -245,7 +256,7 @@ class DeprecatedList(list):
         warnings.warn,
         "EntryPoints list interface is deprecated. Cast to list if needed.",
         DeprecationWarning,
-        stacklevel=2,
+        stacklevel=_pypy_partial(2),
     )
 
     def __setitem__(self, *args, **kwargs):
@@ -394,7 +405,7 @@ class Deprecated:
         warnings.warn,
         "SelectableGroups dict interface is deprecated. Use select.",
         DeprecationWarning,
-        stacklevel=2,
+        stacklevel=_pypy_partial(2),
     )
 
     def __getitem__(self, name):