BUG: Undo behavior change in ma.masked_values(shrink=True)

This change was introduced as part of numpy#10232

Fixes numpy#11112

numpy/ma/core.py

@@ -2319,8 +2319,10 @@ def masked_values(x, value, rtol=1e-5, atol=1e-8, copy=True, shrink=True):
         mask = np.isclose(xnew, value, atol=atol, rtol=rtol)
     else:
         mask = umath.equal(xnew, value)
-    return masked_array(
-        xnew, mask=mask, copy=copy, fill_value=value, shrink=shrink)
+    ret = masked_array(xnew, mask=mask, copy=copy, fill_value=value)
+    if shrink:
+        ret.shrink_mask()
+    return ret
 
 
 def masked_invalid(a, copy=True):

numpy/ma/tests/test_core.py

@@ -4904,6 +4904,12 @@ def test_masked_values(self):
         res = np.ma.masked_values(np.inf, -np.inf)
         assert_equal(res.mask, False)
 
+        res = np.ma.masked_values([1, 2, 3, 4], 5, shrink=True)
+        assert_(res.mask is np.ma.nomask)
+
+        res = np.ma.masked_values([1, 2, 3, 4], 5, shrink=False)
+        assert_equal(res.mask, [False] * 4)
+
 
 def test_masked_array():
     a = np.ma.array([0, 1, 2, 3], mask=[0, 0, 1, 0])