Add a --[no]-packages-dir flag.

lib/src/command.dart

Index: lib/src/command.dart
diff --git a/lib/src/command.dart b/lib/src/command.dart
index d19f9000146a048213d4142eea2dfcc07aeeb55a..ed6c3658b0b5854b18d4ea83334c5805568aff08 100644
--- a/lib/src/command.dart
+++ b/lib/src/command.dart
@@ -37,8 +37,7 @@ abstract class PubCommand extends Command {
   Entrypoint get entrypoint {
     // Lazy load it.
     if (_entrypoint == null) {
-      _entrypoint = new Entrypoint('.', cache,
-          packageSymlinks: globalResults['package-symlinks']);
+      _entrypoint = new Entrypoint('.', cache);
     }
     return _entrypoint;
   }