PathSanitizingFileCheck: improve Python3 compatibility

Adjust the regex match to do a better job of sanitizing the paths.  This
improves the test coverage pass rate with Python 3.  Furthermore, handle
the unicode conversion properly that breaks with Python 3.  This further
improves the Python 3 test coverage pass rate.

Author: compnerd

utils/PathSanitizingFileCheck

@@ -67,20 +67,21 @@ constants.""")
 
     if args.enable_windows_compatibility:
         if args.enable_yaml_compatibility:
-            slashes_re = b'(/|\\\\\\\\|\\\\\\\\\\\\\\\\)'
+            slashes_re = r'(/|\\\\|\\\\\\\\)'
         else:
-            slashes_re = b'(/|\\\\\\\\)'
+            slashes_re = r'(/|\\\\)'
     else:
-        slashes_re = b'/'
+        slashes_re = r'/'
 
-    stdin = io.open(sys.stdin.fileno(), 'rb').read()
+    stdin = io.open(sys.stdin.fileno(), 'r', encoding='utf-8', errors='ignore').read()
 
     for s in args.sanitize_strings:
-        replacement, pattern = s.encode(encoding="utf-8").split(b'=', 1)
+        replacement, pattern = s.split('=', 1)
         # Since we want to use pattern as a regex in some platforms, we need
         # to escape it first, and then replace the escaped slash
         # literal (r'\\/') for our platform-dependent slash regex.
-        stdin = re.sub(re.sub(b'\\\\/', slashes_re, re.escape(pattern)),
+        stdin = re.sub(re.sub('\\\\/' if sys.version_info[0] < 3 else r'[/\\]',
+                              slashes_re, re.escape(pattern)),
                        replacement,
                        stdin)
 
@@ -90,7 +91,7 @@ constants.""")
     else:
         p = subprocess.Popen(
             [args.file_check_path] + unknown_args, stdin=subprocess.PIPE)
-        stdout, stderr = p.communicate(stdin)
+        stdout, stderr = p.communicate(stdin.encode('utf-8'))
         if stdout is not None:
             print(stdout)
         if stderr is not None: