Better compress detection to avoid chunked transfer

src/client.jl

@@ -70,7 +70,9 @@ function send!(client::Client, request::Request; history::Vector{Response}=Respo
     # ensure all Request options are set, using client.options if necessary
     # this works because request.options are null by default whereas client.options always have a default
     update!(request.options, client.options)
-    length(request.body) > request.options.chunksize && (request.options.chunksize = length(request.body) + 1)
+    # if the provided request body is compressed, avoid any chunked transfer since it ruins the compression scheme
+    length(request.body) > 3 && iscompressed(String(request.body)[1:4]) &&
+        length(request.body) > request.options.chunksize && (request.options.chunksize = length(request.body) + 1)
     client.logger != STDOUT && (verbose = true)
     return scheme(request.uri) == "http" ? send!(client, request, getconn(http, client, request , verbose), history, stream, verbose) :
                                            send!(client, request, getconn(https, client, request, verbose), history, stream, verbose)

src/sniff.jl

@@ -1,3 +1,9 @@
+# compression detection
+const ZIP = UInt8[0x50, 0x4b, 0x03, 0x04]
+const GZIP = UInt8[0x1f, 0x8b, 0x08]
+
+iscompressed(bytes) = all(bytes[1:4] .== ZIP) || all(bytes[1:3] .== GZIP)
+
 # Based on the net/http/sniff.go implementation of DetectContentType
 # sniff implements the algorithm described
 # at http://mimesniff.spec.whatwg.org/ to determine the