Sent Accept-Encoding: identity in the head requests. (#155)

It appeared that some s3 servers (Yandex storage in particular)
honour `Accept-Encoding: gzip` request headeer. In such a case
servers can't send `Content-Length` header as transfer size differ
from the body size.
The simplest solution for this problem is to force http-client
to send  `Accept-Encoding: identity` header in the HeadObject
request.

Co-authored-by: Aditya Manthramurthy <donatello@users.noreply.github.com>

src/Network/Minio/S3API.hs

@@ -158,6 +158,10 @@ getObject' bucket object queryParams headers = do
           riObject = Just object,
           riQueryParams = queryParams,
           riHeaders = headers
+               -- This header is required for safety as otherwise http-client,
+               -- sends Accept-Encoding: gzip, and the server may actually gzip
+               -- body. In that case Content-Length header will be missing.
+            <> [("Accept-Encoding", "identity")]
         }
 
 -- | Creates a bucket via a PUT bucket call.
@@ -550,8 +554,11 @@ headObject bucket object reqHeaders = do
           riBucket = Just bucket,
           riObject = Just object,
           riHeaders = reqHeaders
+               -- This header is required for safety as otherwise http-client,
+               -- sends Accept-Encoding: gzip, and the server may actually gzip
+               -- body. In that case Content-Length header will be missing.
+            <> [("Accept-Encoding", "identity")]
         }
-
   maybe (throwIO MErrVInvalidObjectInfoResponse) return
     $ parseGetObjectHeaders object
     $ NC.responseHeaders resp