replace progress-stream with our implementation

upstream is mostly unmaintained

src/progress-stream.js

@@ -0,0 +1,44 @@
+'use strict';
+
+exports = module.exports = ProgressStream;
+
+const stream = require('stream'),
+    TransformStream = stream.Transform;
+
+class ProgressStream extends TransformStream {
+    constructor(options) {
+        super();
+        this._options = Object.assign({ interval: 10 * 1000 }, options);
+        this._transferred = 0;
+        this._delta = 0;
+        this._started = false;
+        this._startTime = null;
+        this._interval = null;
+    }
+
+    _start() {
+        this._startTime = Date.now();
+        this._started = true;
+        this._interval = setInterval(() => {
+            const speed = this._delta * 1000 / this._options.interval;
+            this._delta = 0;
+            this.emit('progress', { speed, transferred: this._transferred });
+        }, this._options.interval);
+    }
+
+    _stop() {
+        clearInterval(this._interval);
+    }
+
+    _transform(chunk, encoding, callback) {
+        if (!this._started) this._start();
+        this._transferred += chunk.length;
+        this._delta += chunk.length;
+        callback(null, chunk);
+    }
+
+    _flush(callback) {
+        this._stop();
+        callback(null);
+    }
+}