TST: Fix bug in test_dtype_with_converters_and_usecols.

The case_sensitive argument to np.recfromcsv has a default value of
'lower'. That value was not previously correctly passed on, but is
now, so the previous expected values in this test were incorrectly
upper cased.

numpy/lib/tests/test_io.py

@@ -1107,13 +1107,13 @@ def test_dtype_with_converters(self):
     def test_dtype_with_converters_and_usecols(self):
         dstr = "1,5,-1,1:1\n2,8,-1,1:n\n3,3,-2,m:n\n"
         dmap = {'1:1':0, '1:n':1, 'm:1':2, 'm:n':3}
-        dtyp = [('E1','i4'),('E2','i4'),('E3','i2'),('N', 'i1')]
+        dtyp = [('e1','i4'),('e2','i4'),('e3','i2'),('n', 'i1')]
         conv = {0: int, 1: int, 2: int, 3: lambda r: dmap[r.decode()]}
         test = np.recfromcsv(TextIO(dstr,), dtype=dtyp, delimiter=',',
                              names=None, converters=conv)
         control = np.rec.array([[1,5,-1,0], [2,8,-1,1], [3,3,-2,3]], dtype=dtyp)
         assert_equal(test, control)
-        dtyp = [('E1','i4'),('E2','i4'),('N', 'i1')]
+        dtyp = [('e1','i4'),('e2','i4'),('n', 'i1')]
         test = np.recfromcsv(TextIO(dstr,), dtype=dtyp, delimiter=',',
                              usecols=(0,1,3), names=None, converters=conv)
         control = np.rec.array([[1,5,0], [2,8,1], [3,3,3]], dtype=dtyp)