better debugs

src/backupformat/tgz.js

@@ -173,6 +173,8 @@ async function upload(backupConfig, remotePath, dataLayout, progressCallback) {
     assert.strictEqual(typeof dataLayout, 'object');
     assert.strictEqual(typeof progressCallback, 'function');
 
+    debug(`upload: Uploading ${dataLayout.toString()} to ${remotePath}`);
+
     return new Promise((resolve, reject) => {
         async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
             retryCallback = once(retryCallback); // protect again upload() erroring much later after tar stream error