Make a bunch of stuff in pub synchronous.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index 8a21eccd5226029cabcb26c1060fe21e07217013..c0cd3b50657e5a9016b1a917d20173e7c96013fb 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -238,7 +238,7 @@ abstract class PubCommand {
       // TODO(rnystrom): Will eventually need better logic to walk up
       // subdirectories until we hit one that looks package-like. For now, just
       // assume the cwd is it.
-      future = Entrypoint.load(path.current, cache);
+      future = defer(() => new Entrypoint(path.current, cache));

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

I think this slightly arcane control flow is an artifact of pre-libv2 APIs.
Suggest:

    defer(() {
      if (requiresEntrypoint) {
        // TODO(rnystrom): Will eventually need better logic to walk up
        // subdirectories until we hit one that looks package-like. For now,
        // just assume the cwd is it.
        this.entrypoint = Entrypoint.load(path.current, cache);
      }
      try {
        var commandFuture = onRun();
        if (commandFuture == null) return true;

        return commandFuture;
      } catch (error, trace) {
        handleError(error, trace);
      }
    }).then((_) => cache_.deleteTempDir()).catchError((asyncError) {
      var e = asyncError.error;
      if (e is PubspecNotFoundException && e.name == null) {
        e = 'Could not find a file named "pubspec.yaml" in the directory '
          '${path.current}.';
      } else if (e is PubspecHasNoNameException && e.name == null) {
        e = 'pubspec.yaml is missing the required "name" field (e.g. "name: '
          '${basename(path.current)}").';
      }

      handleError(e, asyncError.stackTrace);
    }).then((_) {
      // Explicitly exit on success to ensure that any dangling dart:io handles
      // don't cause the process to never terminate.
      exit(0);
    });

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

Beautiful. Tweaked it a bit more, but that's great.

     }
 
     future = future.then((entrypoint) {