filetransfer: remove decompress request parameter

this is never read.

Change-Id: I4c46f140519843a21e452958900e81edd2f78be2

src/libstore/builtins/fetchurl.cc

@@ -38,7 +38,6 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
                the result anyway. */
             FileTransferRequest request(url);
             request.verifyTLS = false;
-            request.decompress = false;
 
             auto decompressor = makeDecompressionSink(
                 unpack && mainUrl.ends_with(".xz") ? "xz" : "none", sink);

src/libstore/filetransfer.hh

@@ -59,7 +59,6 @@ struct FileTransferRequest
     size_t tries = fileTransferSettings.tries;
     unsigned int baseRetryTimeMs = 250;
     ActivityId parentAct;
-    bool decompress = true;
     std::optional<std::string> data;
     std::string mimeType;
     std::function<void(std::string_view data)> dataCallback;

src/nix/prefetch.cc

@@ -98,7 +98,6 @@ std::tuple<StorePath, Hash> prefetchFile(
             FdSink sink(fd.get());
 
             FileTransferRequest req(url);
-            req.decompress = false;
             getFileTransfer()->download(std::move(req), sink);
         }