Make pipeInputToInput yet more resilient to stream closure.

utils/pub/io.dart

Index: utils/pub/io.dart
diff --git a/utils/pub/io.dart b/utils/pub/io.dart
index 06f818d3264189a9ba8e52ce2f84a3f8b6ad23c0..3c703517bd2dbe40acbdbdd3757f58248ab5a6b7 100644
--- a/utils/pub/io.dart
+++ b/utils/pub/io.dart
@@ -623,7 +623,12 @@ Future pipeInputToInput(InputStream source, ListInputStream sink) {
     // Even if the sink is closed and we aren't going to do anything with more
     // data, we still need to drain it from source to work around issue 7218.
     var data = source.read();
-    if (!sink.closed) sink.write(data);
+
+    // Force the program to spin the event loop to work around issue 4222 and
+    // get sink.closed to be set correctly.

[Bob Nystrom, 2012/12/08 03:51:05]

Add some kind of TODO to do something less nasty here?

+    sleep(0).then((_) {
+      if (!sink.closed) sink.write(data);
+    });
   };
   // TODO(nweiz): propagate this error to the sink. See issue 3657.
   source.onError = (e) { throw e; };