Auto-reinstall broken packages in the system cache.

utils/pub/source.dart

Index: utils/pub/source.dart
diff --git a/utils/pub/source.dart b/utils/pub/source.dart
index 777c1a0222fc8f8ffbd1e4e9229cc5ca77009279..a0d804779b05ab5bffa16b5c073f0165adcaeae8 100644
--- a/utils/pub/source.dart
+++ b/utils/pub/source.dart
@@ -108,7 +108,19 @@ abstract class Source {
     var path;
     return systemCacheDirectory(id).then((p) {
       path = p;
-      if (dirExists(path)) return true;
+
+      // See if it's already cached.
+      if (!dirExists(path)) return false;
+
+      // Heuristic to make sure the cached package didn't get deleted
+      // somehow. If the directory is here but there's no pubspec, assume we
+      // got borked and reinstall.

[nweiz, 2013/02/13 00:19:21]

What if just "lib" or the contents of "lib" got wiped out? Isn't that an issue
we were seeing, since that's where the symlink points?

[Bob Nystrom, 2013/02/13 01:27:11]

Oh, great call. Duh.

Fixed this to look for an empty lib dir.

[nweiz, 2013/02/13 02:02:05]

I feel like having the pubspec check as well is still a good idea, in case the
entire directory is erased somehow.

[Bob Nystrom, 2013/02/13 18:00:26]

Done.

+      if (fileExists(join(path, 'pubspec.yaml'))) return true;
+
+      // No pubspec, so wipe it out and reinstall.
+      return deleteDir(path).then((_) => false);
+    }).then((isInstalled) {
+      if (isInstalled) return true;
       ensureDir(dirname(path));
       return install(id, path);
     }).then((found) {