Look for git.cmd on Windows.

utils/pub/git_source.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.
 
 #library('git_source');
 
 #import('io.dart');
 #import('package.dart');
 #import('source.dart');
 #import('source_registry.dart');
@@ skipping 106 matching lines @@
    * Ensure that the canonical clone of the repository referred to by [id] (the
    * one in `<system cache>/git/cache`) exists and is up-to-date. Returns a
    * future that completes once this is finished and throws an exception if it
    * fails.
    */
   Future _ensureRepoCache(PackageId id) {
     var path = _repoCachePath(id);
     return exists(path).chain((exists) {
       if (!exists) return _clone(_getUrl(id), path, mirror: true);
 
-      return runProcess("git", ["fetch"], workingDir: path)
-          .transform((result) {
+      return runGit(["fetch"], workingDir: path).transform((result) {
         if (!result.success) throw 'Git failed.';
         return null;
       });
     });
   }
 
   /**
    * Returns a future that completes to the revision hash of [id].
    */
   Future<String> _revisionAt(PackageId id) {
-    return runProcess("git", ["rev-parse", _getEffectiveRef(id)],
+    return runGit(["rev-parse", _getEffectiveRef(id)],
         workingDir: _repoCachePath(id)).transform((result) {
       if (!result.success) throw 'Git failed.';
       return result.stdout[0];
     });
   }
 
   /**
    * Returns the path to the revision-specific cache of [id].
    */
   Future<String> _revisionCachePath(PackageId id) {
     return _revisionAt(id).transform((rev) {
       var revisionCacheName = '${id.name}-$rev';
       return join(systemCacheRoot, revisionCacheName);
     });
   }
 
   /**
    * Clones the repo at the URI [from] to the path [to] on the local filesystem.
    *
    * If [mirror] is true, create a bare, mirrored clone. This doesn't check out
    * the working tree, but instead makes the repository a local mirror of the
    * remote repository. See the manpage for `git clone` for more information.
    */
   Future _clone(String from, String to, [bool mirror=false]) {
     var args = ["clone", from, to];
     if (mirror) args.insertRange(1, 1, "--mirror");
-    return runProcess("git", args).transform((result) {
+    return runGit(args).transform((result) {
       if (!result.success) throw 'Git failed.';
       return null;
     });
   }
 
   /**
    * Checks out the reference [ref] in [repoPath].
    */
   Future _checkOut(String repoPath, String ref) {
-    return runProcess("git", ["checkout", ref], workingDir: repoPath)
-        .transform((result) {
+    return runGit(["checkout", ref], workingDir: repoPath).transform((result) {
       if (!result.success) throw 'Git failed.';
       return null;
     });
   }
 
   /**
    * Returns the path to the canonical clone of the repository referred to by
    * [id] (the one in `<system cache>/git/cache`).
    */
   String _repoCachePath(PackageId id) {
@@ skipping 44 matching lines @@
 
   /**
    * Returns [description] if it's a description, or [PackageId.description] if
    * it's a [PackageId].
    */
   _getDescription(description) {
     if (description is PackageId) return description.description;
     return description;
   }
 }