Revert r329012 "[lit] Fix problem in how Python versions open files with different encodings"

This doesn't work with Python 2. See this build-in-progress:
http://lab.llvm.org:8011/builders/clang-x86-windows-msvc2015/builds/11105

llvm-svn: 329017

llvm/utils/lit/lit/TestRunner.py

@@ -2,7 +2,6 @@ from __future__ import absolute_import
 import difflib
 import errno
 import functools
-import io
 import itertools
 import getopt
 import os, signal, subprocess, sys
@@ -387,51 +386,9 @@ def executeBuiltinDiff(cmd, cmd_shenv):
             return path, sorted(child_trees)
 
     def compareTwoFiles(filepaths):
-        compare_bytes = False
-        encoding = None
         filelines = []
         for file in filepaths:
-            try:
-                with open(file, 'r') as f:
-                    filelines.append(f.readlines())
-            except UnicodeDecodeError:
-                try:
-                    with open(file, 'r', encoding="utf-8") as f:
-                        filelines.append(f.readlines())
-                    encoding = "utf-8"
-                except:
-                    compare_bytes = True
-
-        if compare_bytes:
-            return compareTwoBinaryFiles(filepaths)
-        else:
-            return compareTwoTextFiles(filepaths, encoding)
-
-    def compareTwoBinaryFiles(filepaths):
-        filelines = []
-        for file in filepaths:
-            with open(file, 'rb') as f:
-                filelines.append(f.readlines())
-
-        exitCode = 0 
-        if hasattr(difflib, 'diff_bytes'):
-            # python 3.5 or newer
-            diffs = difflib.diff_bytes(difflib.unified_diff, filelines[0], filelines[1], filepaths[0].encode(), filepaths[1].encode())
-            diffs = [diff.decode() for diff in diffs]
-        else:
-            # python 2.7
-            func = difflib.unified_diff if unified_diff else difflib.context_diff
-            diffs = func(filelines[0], filelines[1], filepaths[0], filepaths[1])
-
-        for diff in diffs:
-            stdout.write(diff)
-            exitCode = 1
-        return exitCode
-
-    def compareTwoTextFiles(filepaths, encoding):
-        filelines = []
-        for file in filepaths:
-            with open(file, 'r', encoding=encoding) as f:
+            with open(file, 'r') as f:
                 filelines.append(f.readlines())
 
         exitCode = 0