diff -ur patsy-0.5.1/patsy/constraint.py patsy-0.5.1-p39/patsy/constraint.py
--- patsy-0.5.1/patsy/constraint.py 2018-10-28 03:34:36.000000000 +0100
+++ patsy-0.5.1-p39/patsy/constraint.py 2020-01-26 10:58:58.047555461 +0100
@@ -10,7 +10,10 @@
__all__ = ["LinearConstraint"]
import re
-from collections import Mapping
+try:
+ from collections.abc import Mapping
+except ImportError:
+ from collections import Mapping
import six
import numpy as np
from patsy import PatsyError