No longer work around issue 7761.

utils/pub/io.dart

Index: utils/pub/io.dart
diff --git a/utils/pub/io.dart b/utils/pub/io.dart
index 665680e828ebc871f4c4cec1e81cc2a4fd8680ac..2a4e89b1684cfed57bf5d8fed70bcee6ae2ece83 100644
--- a/utils/pub/io.dart
+++ b/utils/pub/io.dart
@@ -610,19 +610,18 @@ class _OutputStreamConsumer implements StreamConsumer<List<int>, dynamic> {
         if (!completed) completer.completeError(e, stack);
         completed = true;
       }
-    }, onDone: () {
-      _outputStream.close();
-      // TODO(nweiz): wait until _outputStream.onClosed is called once issue
-      // 7761 is fixed.
-      if (!completed) completer.complete(null);
-      completed = true;
-    });
+    }, onDone: () => _outputStream.close());
 
     _outputStream.onError = (e) {
       if (!completed) completer.completeError(e);
       completed = true;
     };
 
+    _outputStream.onClosed = () {
+      if (!completed) completer.complete();
+      completed = true;
+    };
+
     return completer.future;
   }
 }