Look for git.cmd on Windows.

utils/tests/pub/test_pub.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.
 
 /**
  * Test infrastructure for testing pub. Unlike typical unit tests, most pub
  * tests are integration tests that stage some stuff on the file system, run
  * pub, and then validate the results. This library provides an API to build
  * tests like that.
  */
@@ skipping 965 matching lines @@
 
   /// Schedule a Git command to run in this repository.
   void scheduleGit(List<String> args) {
     _schedule((parentDir) {
       var gitDir = new Directory(join(parentDir, name));
       return _runGit(args, gitDir);
     });
   }
 
   Future<String> _runGit(List<String> args, Directory workingDir) {
-    return runProcess('git', args, workingDir: workingDir.path).
-      transform((result) {
-        if (!result.success) throw "Error running git: ${result.stderr}";
-        return result.stdout;
-      });
+    return runGit(args, workingDir: workingDir.path).transform((result) {
+      if (!result.success) throw "Error running git: ${result.stderr}";
+      return result.stdout;
+    });
   }
 }
 
 /**
  * Describes a gzipped tar file and its contents.
  */
 class TarFileDescriptor extends Descriptor {
   final List<Descriptor> contents;
 
   TarFileDescriptor(Pattern name, this.contents)
@@ skipping 114 matching lines @@
 }
 
 /**
  * Schedules a callback to be called after Pub is run with [runPub], even if it
  * fails.
  */
 void _scheduleCleanup(_ScheduledEvent event) {
   if (_scheduledCleanup == null) _scheduledCleanup = [];
   _scheduledCleanup.add(event);
 }