unsafeReceiveResponse that does not consume body

This works when you know there is no body, no matter what the headers
say (HEAD requests, aesiniath#114)

This also works when the handler consumes whatever part of the body you
actually want to use, and then you close the connection afterwards (no
reusing for pipelining!)  Sometimes this is a lot faster than using
pipelining if you can, for example, skip a many GB download (aesiniath#113)

lib/Network/Http/Client.hs

@@ -133,6 +133,7 @@ module Network.Http.Client (
     -- * Processing HTTP response
     receiveResponse,
     receiveResponseRaw,
+    unsafeReceiveResponse,
     UnexpectedCompression,
     StatusCode,
     getStatusCode,

lib/Network/Http/Connection.hs

@@ -30,6 +30,7 @@ module Network.Http.Connection (
     sendRequest,
     receiveResponse,
     receiveResponseRaw,
+    unsafeReceiveResponse,
     UnexpectedCompression,
     emptyBody,
     fileBody,
@@ -490,6 +491,22 @@ receiveResponseRaw c handler = do
   where
     i = cIn c
 
+--
+-- | Handle the response coming back from the server. This function
+-- is the same as receiveResponse, but it does not consume the body for
+-- you after the handler is done.  This means that it can only be safely used
+-- if the handler will fully consume the body, there is no body, or when
+-- the connection is not being reused (no pipelining).
+--
+unsafeReceiveResponse :: Connection -> (Response -> InputStream ByteString -> IO β) -> IO β
+unsafeReceiveResponse c handler = do
+    p  <- readResponseHeader i
+    i' <- readResponseBody p i
+
+    handler p i'
+  where
+    i = cIn c
+
 
 --
 -- | Use this for the common case of the HTTP methods that only send