Use a bare git repository for the repo cache.

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 34 matching lines @@
       }
 
       return ensureDir(join(systemCacheRoot, 'cache'));
     }).chain((_) => _ensureRepoCache(id))
       .chain((_) => _revisionCachePath(id))
       .chain((path) {
       revisionCachePath = path;
       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);
       return _checkOut(revisionCachePath, ref);
     }).chain((_) => Package.load(revisionCachePath, systemCache.sources));
   }
 
   /**
    * The package name of a Git repo is the name of the directory into which
    * it'll be cloned.
@@ skipping 49 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);
+      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;
       });
     });
   }
 
   /**
    * Returns a future that completes to the revision hash of [id].
    */
   Future<String> _revisionAt(PackageId id) {
     return runProcess("git", ["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.

[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;
     });
   }
 
   /**
    * Checks out the reference [ref] in [repoPath].
    */
   Future _checkOut(String repoPath, String ref) {
     return runProcess("git", ["checkout", ref], workingDir: repoPath)
@@ skipping 55 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;
   }
 }