Fix an edge case in the dependency computer.

test/dependency_computer/dev_transformers_test.dart

 // Copyright (c) 2014, 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 '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
@@ skipping 70 matching lines @@
         "name": "foo",
         "version": "1.0.0",
         "transformers": [{"foo": {"\$include": "bin/foo.dart"}}]
       }),
       d.dir("lib", [d.file("foo.dart", transformer())]),
       d.dir("test", [d.file("foo_test.dart", "")])
     ]).create();
 
     expectDependencies({"foo": []});
   });
+
+  // Regression test for #1291
+  integration("doesn't return a dependency's transformer that can't run on lib "
+      "when the app's transformer imports the dependency's", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "transformers": ["myapp"]
+      }),
+      d.dir("lib", [
+        d.file("myapp.dart", transformer(['package:foo/foo.dart']))
+      ])
+    ]).create();
+
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "transformers": [
+          ["foo/bar"],
+          [{"foo": {"\$include": "test/foo_test.dart"}}]
+        ]
+      }),
+      d.dir("lib", [
+        d.file("foo.dart", transformer()),
+        d.file("bar.dart", transformer())
+      ]),
+      d.dir("test", [d.file("foo_test.dart", "")])
+    ]).create();
+
+    expectDependencies({
+      'foo/bar': [],
+      'myapp': ['foo/bar']
+    });
+  });
 }