1111import contextlib
1212import functools
1313import gzip
14+ import inspect
1415import itertools
1516import math
1617import operator
@@ -1961,6 +1962,10 @@ def _array_patch_perimeters(x, rstride, cstride):
19611962def _setattr_cm (obj ,** kwargs ):
19621963"""
19631964 Temporarily set some attributes; restore original state at context exit.
1965+
1966+ .. warning ::
1967+
1968+ This is not threadsafe.
19641969 """
19651970sentinel = object ()
19661971origs = {}
@@ -1978,14 +1983,18 @@ def _setattr_cm(obj, **kwargs):
19781983# we want to set the original value back.
19791984if isinstance (cls_orig ,property ):
19801985origs [attr ]= orig
1986+
1987+ # detect when we have Python Descriptors that supports
1988+ # setting so we will need to restore it
1989+ #
1990+ # https://docs.python.org/3/howto/descriptor.html
1991+ if hasattr (inspect .getattr_static (type (obj ),attr ),'__set__' ):
1992+ origs [attr ]= orig
1993+
19811994# otherwise this is _something_ we are going to shadow at
19821995# the instance dict level from higher up in the MRO. We
19831996# are going to assume we can delattr(obj, attr) to clean
1984- # up after ourselves. It is possible that this code will
1985- # fail if used with a non-property custom descriptor which
1986- # implements __set__ (and __delete__ does not act like a
1987- # stack). However, this is an internal tool and we do not
1988- # currently have any custom descriptors.
1997+ # up after ourselves.
19891998else :
19901999origs [attr ]= sentinel
19912000