Avoid passing absolute path to 7zip.

utils/pub/io.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 library io;
 
 import 'dart:io';
@@ skipping 672 matching lines @@
     for (var file in files) {
       if (new Path(file).extension == 'tar') {
         tarFile = file;
         break;
       }
     }
 
     if (tarFile == null) throw 'The gzip file did not contain a tar file.';
 
     // Untar the archive into the destination directory.
-    return runProcess(command, ['x', '-o"$destination"', tarFile],
-        workingDir: tempDir);
+    return runProcess(command, ['x', tarFile], workingDir: destination);
   }).chain((result) {
     if (result.exitCode != 0) {
       throw 'Could not un-tar (exit code ${result.exitCode}). Error:\n'
           '${Strings.join(result.stdout, "\n")}\n'
           '${Strings.join(result.stderr, "\n")}';
     }
 
     // Clean up the temp directory.
     // TODO(rnystrom): Should also delete this if anything fails.
     return deleteDir(tempDir);
@@ skipping 57 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }