Support activating packages from local paths.

sdk/lib/_internal/pub/test/global/activate/git_package_missing_ref_test.dart

Index: sdk/lib/_internal/pub/test/global/activate/git_package_missing_ref_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/activate/git_package_missing_ref_test.dart b/sdk/lib/_internal/pub/test/global/activate/git_package_missing_ref_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ac54b93bef08ddd7cd06eb4cc69c7406188f2476
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/global/activate/git_package_missing_ref_test.dart
@@ -0,0 +1,25 @@
+// 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.
+
+import '../../../lib/src/exit_codes.dart' as exit_codes;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration('fails if no git ref was given', () {
+    ensureGit();
+
+    schedulePub(args: ["global", "activate", "-sgit", "foo"],
+        error: """
+            Must provide a Git ref for the package.
+
+            Usage: pub global activate [--source source] <package> [version]
+            -h, --help      Print usage information for this command.
+            -s, --source    The source used to find the package.
+                            [git, hosted (default), path]
+
+            Run "pub help" to see global options.""",
+        exitCode: exit_codes.USAGE);
+  });
+}