Use a bare git repository for the repo cache.

utils/pub/git_source.dart

Index: utils/pub/git_source.dart
diff --git a/utils/pub/git_source.dart b/utils/pub/git_source.dart
index a815feb2c7638dc47abaaf70223c5cb4524fb957..35f4947e4bb35973f14f93e02c4e05e14a0a6491 100644
--- a/utils/pub/git_source.dart
+++ b/utils/pub/git_source.dart
@@ -52,7 +52,7 @@ class GitSource extends Source {
       return exists(revisionCachePath);
     }).chain((exists) {
       if (exists) return new Future.immediate(null);
-      return _clone(_repoCachePath(id), revisionCachePath);
+      return _clone(_repoCachePath(id), revisionCachePath, mirror: false);
     }).chain((_) {
       var ref = _getEffectiveRef(id);
       if (ref == 'HEAD') return new Future.immediate(null);
@@ -122,10 +122,12 @@ class GitSource extends Source {
   Future _ensureRepoCache(PackageId id) {
     var path = _repoCachePath(id);
     return exists(path).chain((exists) {
-      if (!exists) return _clone(_getUrl(id), path);
+      if (!exists) return _clone(_getUrl(id), path, mirror: true);
 
-      return runProcess("git", ["pull", "--force"], workingDir: path)
+      return runProcess("git", ["fetch"], workingDir: path)
           .transform((result) {
+        print(result.stdout);
+        print(result.stderr);

[Bob Nystrom, 2012/09/05 00:56:04]

Remove these.

[nweiz, 2012/09/05 21:10:42]

Done.

         if (!result.success) throw 'Git failed.';
         return null;
       });
@@ -156,8 +158,10 @@ class GitSource extends Source {
   /**
    * Clones the repo at the URI [from] to the path [to] on the local filesystem.

[Bob Nystrom, 2012/09/05 00:56:04]

Can you explain what "mirror" is for here?

[nweiz, 2012/09/05 21:10:42]

Done.

    */
-  Future _clone(String from, String to) {
-    return runProcess("git", ["clone", from, to]).transform((result) {
+  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) {
       if (!result.success) throw 'Git failed.';
       return null;
     });