PY3 MimeTypes wants files in text mode.

See http://hg.python.org/cpython/file/2766320bdb10/Lib/mimetypes.py#l202

before: 455 failed, 248 passed, 10 skipped, 8 warnings, 55 error in 88.36 seconds
after:  466 failed, 253 passed, 12 skipped, 8 warnings, 49 error in 90.15 seconds

scrapy/responsetypes.py

@@ -6,7 +6,7 @@
 
 from mimetypes import MimeTypes
 from pkgutil import get_data
-from io import BytesIO
+from io import StringIO
 import six
 
 from scrapy.http import Response
@@ -33,8 +33,8 @@ class ResponseTypes(object):
     def __init__(self):
         self.classes = {}
         self.mimetypes = MimeTypes()
-        mimedata = get_data('scrapy', 'mime.types')
-        self.mimetypes.readfp(BytesIO(mimedata))
+        mimedata = get_data('scrapy', 'mime.types').decode('utf8')
+        self.mimetypes.readfp(StringIO(mimedata))
         for mimetype, cls in six.iteritems(self.CLASSES):
             self.classes[mimetype] = load_object(cls)