Don't allow packages to depend on themselves.

sdk/lib/_internal/pub/test/pub_install_and_update_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library pub_tests;
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
@@ skipping 95 matching lines @@
       d.dir(appPath, [
         d.appPubspec({
           "foo": {"path": "../deps/foo"},
           "bar": {"path": "../deps/bar"}
         })
       ]).create();
 
       pubCommand(command,
           error: new RegExp("^Incompatible dependencies on 'baz':\n"));
     });
+
+    integration('does not allow a dependency on itself', () {
+      d.dir(appPath, [
+        d.appPubspec({
+          "myapp": {"path": "."}
+        })
+      ]).create();
+
+      pubCommand(command,
+          error: new RegExp("Package 'myapp' cannot depend on itself."));
+    });
+
+    integration('does not allow a dev dependency on itself', () {
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "dev_dependencies": {
+            "myapp": {"path": "."}
+          }
+        })
+      ]).create();
+
+      pubCommand(command,
+          error: new RegExp("Package 'myapp' cannot depend on itself."));
+    });
   });
 }