Revert "Handle StopIteration in Python 3.7+"

This reverts commit 701712f.

Author: groutr

toolz/itertoolz.py

@@ -375,11 +375,8 @@ def second(seq):
     'B'
     """
     seq = iter(seq)
-    try:
-        next(seq)
-        return next(seq)
-    except StopIteration:
-        raise
+    next(seq)
+    return next(seq)
 
 
 def nth(n, seq):

toolz/tests/test_itertoolz.py

@@ -17,8 +17,6 @@
 from toolz.compatibility import range, filter
 from operator import add, mul
 
-import pytest
-
 
 # is comparison will fail between this and no_default
 no_default2 = loads(dumps('__no__default__'))
@@ -145,12 +143,6 @@ def test_second():
     assert second('ABCDE') == 'B'
     assert second((3, 2, 1)) == 2
     assert isinstance(second({0: 'zero', 1: 'one'}), int)
-    assert second(x for x in range(2)) == 1
-
-    # Python 3.7, StopIteration should be raised if iterable too short
-    with pytest.raises(StopIteration):
-        second([])
-        second([0])
 
 
 def test_last():