fix(client): improve keep-alive of bodyless Responses

src/client/response.rs

@@ -47,9 +47,9 @@ impl Response {
             version: version,
             headers: headers,
             url: url,
-            message: message,
             status_raw: raw_status,
-            is_drained: false,
+            is_drained: !message.has_body(),
+            message: message,
         })
     }
 

src/http/h1.rs

@@ -203,6 +203,13 @@ impl HttpMessage for Http11Message {
         })
     }
 
+    fn has_body(&self) -> bool {
+        match self.reader {
+            Some(EmptyReader(..)) => false,
+            _ => true
+        }
+    }
+
     #[cfg(feature = "timeouts")]
     #[inline]
     fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {

src/http/h2.rs

@@ -400,6 +400,10 @@ impl<S> HttpMessage for Http2Message<S> where S: CloneableStream {
         Ok(head)
     }
 
+    fn has_body(&self) -> bool {
+        true
+    }
+
     #[cfg(feature = "timeouts")]
     #[inline]
     fn set_read_timeout(&self, _dur: Option<Duration>) -> io::Result<()> {

src/http/message.rs

@@ -72,6 +72,8 @@ pub trait HttpMessage: Write + Read + Send + Any + Typeable + Debug {
     fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()>;
     /// Closes the underlying HTTP connection.
     fn close_connection(&mut self) -> ::Result<()>;
+    /// Returns whether the incoming message has a body.
+    fn has_body(&self) -> bool;
 }
 
 impl HttpMessage {