cashew: patch in libcurl_http_fetcher changes from update_engine

src/libcurl_http_fetcher.h

Index: src/libcurl_http_fetcher.h
diff --git a/src/libcurl_http_fetcher.h b/src/libcurl_http_fetcher.h
index 7d066823a8751d638ee868bd7645a1e39d2bad3d..144a7a8cd46674c88487b8cf2fccca877d603920 100644
--- a/src/libcurl_http_fetcher.h
+++ b/src/libcurl_http_fetcher.h
@@ -124,10 +124,12 @@ class LibcurlHttpFetcher : public HttpFetcher {
   CURLM *curl_multi_handle_;
   CURL *curl_handle_;
 
-  // a list of all file descriptors that we're waiting on from the
-  // glib main loop
+  // Lists of all read(0)/write(1) file descriptors that we're waiting on from
+  // the glib main loop. libcurl may open/close descriptors and switch their
+  // directions so maintain two separate lists so that watch conditions can be
+  // set appropriately.
   typedef std::map<int, std::pair<GIOChannel*, guint> > IOChannels;
-  IOChannels io_channels_;
+  IOChannels io_channels_[2];
 
   // if non-NULL, a timer we're waiting on. glib main loop will call us back
   // when it fires.