Make a bunch of stuff in pub synchronous.

utils/pub/utils.dart

Index: utils/pub/utils.dart
diff --git a/utils/pub/utils.dart b/utils/pub/utils.dart
index 8d17f9550430670d29fc1d4bcb1fee27433911f1..b3eb4677e5c688bf6908740d0a6484a4bfd26854 100644
--- a/utils/pub/utils.dart
+++ b/utils/pub/utils.dart
@@ -104,6 +104,12 @@ String sha1(String source) {
   return CryptoUtils.bytesToHex(sha.close());
 }
 
+/// Invokes the given callback asynchronously. Returns a [Future] that completes
+/// to the result of [callback].

[nweiz, 2013/02/01 02:05:55]

Move all those comments about error-capturing in here.

[Bob Nystrom, 2013/02/01 23:17:21]

Done.

+Future defer(callback()) {
+  return new Future.immediate(null).then((_) => callback());
+}
+
 /// Returns a [Future] that completes in [milliseconds].
 Future sleep(int milliseconds) {
   var completer = new Completer();