do not try to compress if not sure about the file content

weed/storage/needle/needle_parse_upload.go

@@ -75,7 +75,7 @@ func ParseUpload(r *http.Request, sizeLimit int64, bytesBuffer *bytes.Buffer) (p
 		if mimeType == "application/octet-stream" {
 			mimeType = ""
 		}
-		if shouldBeCompressed, iAmSure := util.IsCompressableFileType(ext, mimeType); mimeType == "" && !iAmSure || shouldBeCompressed && iAmSure {
+		if shouldBeCompressed, iAmSure := util.IsCompressableFileType(ext, mimeType); shouldBeCompressed && iAmSure {
 			// println("ext", ext, "iAmSure", iAmSure, "shouldBeCompressed", shouldBeCompressed, "mimeType", pu.MimeType)
 			if compressedData, err := util.GzipData(pu.Data); err == nil {
 				if len(compressedData)*10 < len(pu.Data)*9 {