Make version.dart ready for svn 1.7 checkouts

tools/release/version.dart

 // Copyright (c) 2013, 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.
 
 /**
  * This file contains functionality for getting dart version numbers using
  * our standard version construction method. Systems that does not include this
  * file should emulate the structure for revision numbers that we have here.
  *
  * The version number of a dart build is constructed as follows:
@@ skipping 171 matching lines @@
       key = "USERNAME";
     }
     if (!Platform.environment.containsKey(key)) return "";
     var username = Platform.environment[key];
     // If this is a production build, i.e., this is something we are shipping,
     // don't suffix  the version with the username.
     if (isProductionBuild(username)) return "";
     return username;
   }
 
-  bool isGitRepository() {
+  RepositoryType get repositoryType {
+    bool isWindows = Platform.operatingSystem == 'windows';
+    bool hasDirectory(path, name) {
+      return new Directory.fromPath(path.append(name)).existsSync();
+    }
+    bool isFileSystemRoot(absolutePath) {
+      if (isWindows) {
+        return "${absolutePath.directoryPath}" == '/';
+      }
+      return "$absolutePath" == '/';
+    }
+
     var currentPath = new Path(new Directory.current().path);
-    while (!new Directory.fromPath(currentPath.append(".git")).existsSync()) {
-      currentPath = currentPath.directoryPath;
-      if (currentPath.toString() == "/") {
+    while (true) {
+      if (hasDirectory(currentPath, '.svn')) {
+        return RepositoryType.SVN;
+      } else if (hasDirectory(currentPath, '.git')) {
+        return RepositoryType.GIT;
+      }
+      if (isFileSystemRoot(currentPath)) {
         break;
       }
+      currentPath = currentPath.directoryPath;
     }
-    return new Directory.fromPath(currentPath.append(".git")).existsSync();
-  }
-
-  RepositoryType get repositoryType {
-    if (new Directory(".svn").existsSync()) return RepositoryType.SVN;
-    if (isGitRepository()) return RepositoryType.GIT;
     return RepositoryType.UNKNOWN;
   }
 }
 
 class RepositoryType {
   static final RepositoryType SVN = const RepositoryType("SVN");
   static final RepositoryType GIT = const RepositoryType("GIT");
   static final RepositoryType UNKNOWN = const RepositoryType("UNKNOWN");
 
   const RepositoryType(String this.name);
 
   static RepositoryType guessType() {
     if (new Directory(".svn").existsSync()) return RepositoryType.SVN;
     if (new Directory(".git").existsSync()) return RepositoryType.GIT;
     return RepositoryType.UNKNOWN;
   }
 
   String toString() => name;
 
   final String name;
 }