Teach E265 fixer to ignore special comments even in the middle of files

This appears to be expected for compatibility, though is a somewhat
unexpected behaviour given that these comments are almost certainly
not actually 'shebang' comments.

autopep8.py

@@ -830,6 +830,10 @@ def fix_e265(self, result):
         hashes = line[:pos]
         comment = line[pos:].lstrip(' \t')
 
+        # Ignore special comments, even in the middle of the file.
+        if comment.startswith('!'):
+            return
+
         fixed = indent + hashes + (' ' + comment if comment.strip() else '\n')
 
         self.source[result['line'] - 1] = fixed

test/test_autopep8.py

@@ -2232,6 +2232,16 @@ def test_e265(self):
         with autopep8_context(line) as result:
             self.assertEqual(fixed, result)
 
+    def test_e265_ignores_special_comments(self):
+        line = "#!python\n456\n"
+        with autopep8_context(line) as result:
+            self.assertEqual(line, result)
+
+    def test_e265_ignores_special_comments_in_middle_of_file(self):
+        line = "123\n\n#!python\n456\n"
+        with autopep8_context(line) as result:
+            self.assertEqual(line, result)
+
     def test_e265_only(self):
         line = "##A comment\n#B comment\n123\n"
         fixed = "## A comment\n# B comment\n123\n"