Add “pub cache repair” to forcibly re-install previously cached packages.

sdk/lib/_internal/pub/test/cache/repair/reinstalls_git_packages_test.dart

Index: sdk/lib/_internal/pub/test/cache/repair/reinstalls_git_packages_test.dart
diff --git a/sdk/lib/_internal/pub/test/cache/repair/reinstalls_git_packages_test.dart b/sdk/lib/_internal/pub/test/cache/repair/reinstalls_git_packages_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..138cd04e5445e3ec2fcab1fb0424e2a5591bec89
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+++ b/sdk/lib/_internal/pub/test/cache/repair/reinstalls_git_packages_test.dart
@@ -0,0 +1,68 @@
+// 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 'package:path/path.dart' as path;
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../../../lib/src/io.dart';
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration('reinstalls previously cached git packages', () {
+    // Create two cached revisions of foo.
+    d.git('foo.git', [
+      d.libDir('foo'),
+      d.libPubspec('foo', '1.0.0')
+    ]).create();
+
+    d.appDir({"foo": {"git": "../foo.git"}}).create();
+    pubGet();
+
+    d.git('foo.git', [
+      d.libDir('foo'),
+      d.libPubspec('foo', '1.0.1')
+    ]).commit();
+
+    pubUpgrade();
+
+    // Break them.
+    var fooDirs;
+    schedule(() {
+      // Find the cached foo packages for each revision.
+      var gitCacheDir = path.join(sandboxDir, cachePath, "git");
+      fooDirs = listDir(gitCacheDir)
+          .where((dir) => path.basename(dir).startsWith("foo-")).toList();
+
+      // Delete "foo.dart" from them.
+      for (var dir in fooDirs) {
+        deleteEntry(path.join(dir, "lib", "foo.dart"));
+      }
+    });
+
+    // Repair them.
+    schedulePub(args: ["cache", "repair"],
+        output: '''
+          Resetting Git repository for foo 1.0.0...
+          Resetting Git repository for foo 1.0.1...
+          Reinstalled 2 packages.''');
+
+    // The missing libraries should have been replaced.
+    schedule(() {
+      var fooLibs = fooDirs.map((dir) {
+        var fooDirName = path.basename(dir);
+        return d.dir(fooDirName, [
+          d.dir("lib", [d.file("foo.dart", 'main() => "foo";')])
+        ]);
+      }).toList();
+
+      d.dir(cachePath, [
+        d.dir("git", fooLibs)
+      ]).validate();
+    });
+  });
+}