Fix flake8 E305 and E306 errors

These errors started to appear with flake8-3.1.1, while they don't appear with
version 3.1.0 (weird).

_pytest/_code/code.py

@@ -343,6 +343,7 @@ class Traceback(list):
             l.append(entry.frame.f_locals)
         return None
 
+
 co_equal = compile('__recursioncache_locals_1 == __recursioncache_locals_2',
                    '?', 'eval')
 
@@ -846,6 +847,7 @@ def getrawcode(obj, trycall=True):
                     return x
         return obj
 
+
 if sys.version_info[:2] >= (3, 5):  # RecursionError introduced in 3.5
     def is_recursion_error(excinfo):
         return excinfo.errisinstance(RecursionError)  # noqa