Improve detection of "nosec" clause

Author: ehooo

bandit/core/manager.py

@@ -264,9 +264,14 @@ def _parse_file(self, fname, fdata, new_files_list):
             lines = data.splitlines()
             self.metrics.begin(fname)
             self.metrics.count_locs(lines)
-            if self.ignore_nosec:
-                nosec_lines = set()
+
+            nosec_lines = set()
+            if not six.PY2 and isinstance(data, bytes):
+                has_nosec = b'nosec' in data
             else:
+                has_nosec = 'nosec' in data
+
+            if not self.ignore_nosec and has_nosec:
                 try:
                     fdata.seek(0)
                     if six.PY2:

tests/functional/test_runtime.py

@@ -5,7 +5,6 @@
 import os
 import subprocess
 
-import six
 import testtools
 
 
@@ -103,12 +102,7 @@ def test_example_nonsense2(self):
         )
         self.assertEqual(0, retcode)
         self.assertIn("Files skipped (1):", output)
-        if six.PY2:
-            self.assertIn("nonsense2.py (exception while scanning file)",
-                          output)
-        else:
-            self.assertIn("nonsense2.py (syntax error while parsing AST",
-                          output)
+        self.assertIn("nonsense2.py (exception while scanning file)", output)
 
     def test_example_imports(self):
         (retcode, output) = self._test_example(['bandit', ], ['imports.py', ])