Revert "Merge branch 'revert-63b91c95' into 'master'"

This reverts commit ba2fb9c53a8316642249598f599bbf7608d54260, reversing
changes made to 63b91c95ea7795e3c3c90f2d643f685bfff312e9.

1 files changed, 3 insertions, 6 deletions

diff --git a/src/flake8/processor.py b/src/flake8/processor.py
index fdf0a98..18f9f1d 100644
--- a/src/flake8/processor.py
+++ b/src/flake8/processor.py
@@ -1,6 +1,5 @@
 """Module containing our file processor that tokenizes a file for checks."""
 import contextlib
-import io
 import logging
 import sys
 import tokenize
@@ -308,11 +307,9 @@ class FileProcessor(object):
     def _readlines_py3(self):
         # type: () -> List[str]
         try:
-            with open(self.filename, "rb") as fd:
-                (coding, lines) = tokenize.detect_encoding(fd.readline)
-                textfd = io.TextIOWrapper(fd, coding, line_buffering=True)
-                return [l.decode(coding) for l in lines] + textfd.readlines()
-        except (LookupError, SyntaxError, UnicodeError):
+            with tokenize.open(self.filename) as fd:
+                return fd.readlines()
+        except (SyntaxError, UnicodeError):
             # If we can't detect the codec with tokenize.detect_encoding, or
             # the detected encoding is incorrect, just fallback to latin-1.
             with open(self.filename, encoding="latin-1") as fd: