tests: in filterpyflakes, tolerate non-ascii file contents

tests/filterpyflakes.py

@@ -1,36 +1,35
 #!/usr/bin/env python3
 
 # Filter output by pyflakes to control which warnings we check
 
 
 import re
 import sys
 
 lines = []
 for line in sys.stdin:
     # We blacklist tests that are too noisy for us
     pats = [
         r"undefined name 'WindowsError'",
         r"redefinition of unused '[^']+' from line",
         # for cffi, allow re-exports from pure.*
         r"cffi/[^:]*:.*\bimport \*' used",
         r"cffi/[^:]*:.*\*' imported but unused",
     ]
 
     keep = True
     for pat in pats:
         if re.search(pat, line):
             keep = False
             break  # pattern matches
     if keep:
         fn = line.split(':', 1)[0]
-        f = open(fn)
-        data = f.read()
-        f.close()
-        if 'no-' 'check-code' in data:
+        with open(fn, 'rb') as f:
+            data = f.read()
+        if b'no-' b'check-code' in data:
             continue
         lines.append(line)
 
 for line in lines:
     sys.stdout.write(line)
 print()