Added response type recognition to local file urls

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40790

scrapy/trunk/scrapy/core/downloader/handlers.py

@@ -104,5 +104,9 @@ def download_file(request, spider) :
     """Return a deferred for a file download."""
     filepath = request.url.split("file://")[1]
     with open(filepath) as f:
-        response = Response(url=request.url, body=f.read())
+        body = f.read()
+        respcls = responsetypes.from_filename(filepath)
+        respcls = responsetypes.from_body(body) if respcls is Response else respcls
+        response = respcls(url=request.url, body=body)
+
     return defer_succeed(response)

scrapy/trunk/scrapy/core/downloader/responsetypes.py

@@ -67,13 +67,10 @@ class ResponseTypes(object):
         return self.from_mimetype(mimetypes.guess_type(url)[0])
 
     def from_body(self, body):
-        """Try to guess the appropiate response based on the body content. 
-        
+        """Try to guess the appropiate response based on the body content.
         This method is a bit magic and could be improved in the future, but
         it's not meant to be used except for special cases where response types
-        cannot be guess using more straightforward methods.
-
-        """
+        cannot be guess using more straightforward methods."""
         chunk = body[:5000]
         if isbinarytext(chunk):
             return self.from_mimetype('application/octet-stream')