keep pypy check in cython version

Author: jorisvandenbossche

pandas/_libs/internals.pyx

@@ -23,10 +23,10 @@ from numpy cimport (
 cnp.import_array()
 
 from pandas._libs.algos import ensure_int64
+from pandas.compat import PYPY
 from pandas.errors import ChainedAssignmentError
 from pandas.errors.cow import _chained_assignment_msg
 
-
 from pandas._libs.util cimport (
     is_array,
     is_integer_object,
@@ -1031,11 +1031,13 @@ cdef class SetitemMixin:
     # class used in DataFrame and Series for checking for chained assignment
 
     def __setitem__(self, key, value) -> None:
-        cdef bint is_unique = _is_unique_referenced_temporary(self)
-        if is_unique:
-            warnings.warn(
-                _chained_assignment_msg, ChainedAssignmentError, stacklevel=1
-            )
+        cdef bint is_unique = 0
+        if not PYPY:
+            _is_unique_referenced_temporary(self)
+            if is_unique:
+                warnings.warn(
+                    _chained_assignment_msg, ChainedAssignmentError, stacklevel=1
+                )
         self._setitem(key, value)
 
     def __delitem__(self, key) -> None: