Fix recursion in pytest.approx() with arrays in numpy<1.13

changelog/3748.bugfix.rst

@@ -0,0 +1 @@
+Fix infinite recursion in ``pytest.approx`` with arrays in ``numpy<1.13``.

src/_pytest/python_api.py

@@ -211,7 +211,7 @@ class ApproxScalar(ApproxBase):
         the pre-specified tolerance.
         """
         if _is_numpy_array(actual):
-            return all(a == self for a in actual.flat)
+            return all(self == a for a in actual.flat)
 
         # Short-circuit exact equality.
         if actual == self.expected: