Make the command cache use the directory name as part of the cache key

test/variables/commands/repeated_multidir/repeated_command_common.gypi

+# Copyright 2014 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'variables': {
+    # This command will be run from the directories of the .gyp files that
+    # include this .gypi, the subdirectories dir_1 and dir_2, so use a
+    # relative path from those directories to the script.
+    'observed_value': '<!(python ../print_cwd_basename.py)',
+  },
+  'targets': [
+    {
+      'target_name': '<(target_name)',
+      'type': 'none',
+      'conditions': [
+        ['observed_value != expected_value', {
+          # Attempt to expand an undefined variable. This triggers a GYP
+          # error.
+          'assertion': '<(observed_value_must_equal_expected_value)',
+        }],
+      ],
+    },
+  ],
+}