fix fetchers.usingCurl to properly work with ExceptionWrappingFetcher

openid/fetchers.py

@@ -93,7 +93,10 @@ def setDefaultFetcher(fetcher, wrap_exceptions=True):
 
 def usingCurl():
     """Whether the currently set HTTP fetcher is a Curl HTTP fetcher."""
-    return isinstance(getDefaultFetcher(), CurlHTTPFetcher)
+    fetcher = getDefaultFetcher()
+    if isinstance(fetcher, ExceptionWrappingFetcher):
+        fetcher = fetcher.fetcher
+    return isinstance(fetcher, CurlHTTPFetcher)
 
 class HTTPResponse(object):
     """XXX document attributes"""