Override dependencies of locked packages

Partially addresses #1853

lib/src/solver/package_lister.dart

@@ -227,6 +227,7 @@ class PackageLister {
         return incompatibilities;
       } else {
         return pubspec.dependencies.values
+            .where((range) => !_overriddenPackages.contains(range.name))
             .map((range) => _dependency(depender, range))
             .toList();
       }

test/get/overrides_locked_test.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS d.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 d.file.
+
+import 'package:test/test.dart';
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+
+main() {
+  // Regression test for #1853
+  test("overrides a locked package's dependency", () async {
+    await servePackages((builder) {
+      builder.serve("foo", "1.2.3", deps: {"bar": "1.2.3"});
+      builder.serve("bar", "1.2.3");
+    });
+
+    await d.dir('bar',
+        [d.libDir('bar', 'bar 0.0.1'), d.libPubspec('bar', '0.0.1')]).create();
+
+    await d.appDir({
+      "foo": "any"
+    }).create();
+
+    await pubGet();
+
+    await d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {
+      "foo": "any"
+    },
+        "dependency_overrides": {"bar": {"path": "../bar"}}
+      })
+    ]).create();
+
+    await pubGet();
+
+    await d.appPackagesFile({"foo": "1.2.3", "bar": "../bar"}).validate();
+  });
+}