[gnome-ostree] build: Fix up case where we have no previous build for a component

[Colin Walters <walters src gnome org>]

commit b605108a965039aa4935986daa34cda36c0517bb
Author: Colin Walters <walters verbum org>
Date:   Tue Sep 10 18:33:39 2013 -0400

    build: Fix up case where we have no previous build for a component
    
    There is no parent.  While we're here, let's change things so that we
    always give null for a parent to commit.

 src/js/tasks/task-build.js |   17 +++++++++++------
 1 files changed, 11 insertions(+), 6 deletions(-)
---
diff --git a/src/js/tasks/task-build.js b/src/js/tasks/task-build.js
index 3cd7a8b..de96aba 100644
--- a/src/js/tasks/task-build.js
+++ b/src/js/tasks/task-build.js
@@ -519,14 +519,19 @@ const TaskBuild = new Lang.Class({
         return file;
     },
 
-    _commit: function(branch, subject, file, cancellable) {
+    _commit: function(branch, subject, file, cancellable, params) {
+       params = Params.parse(params, { withParent: true });
         let [, parentRev] = this.ostreeRepo.resolve_rev(branch, true);
-        let [, parent] = this.ostreeRepo.read_commit(parentRev, cancellable);
-
-        let changed = !file.equal(parent);
+       let changed;
+       if (parentRev) {
+            let [, parent] = this.ostreeRepo.read_commit(parentRev, cancellable);
+            changed = !file.equal(parent);
+       } else {
+           changed = true;
+       }
 
         if (changed) {
-            let [, rev] = this.ostreeRepo.write_commit(parentRev, subject, "", null, file, cancellable);
+            let [, rev] = this.ostreeRepo.write_commit(params.withParent ? parentRev : null, subject, "", 
null, file, cancellable);
             this.ostreeRepo.transaction_set_ref(null, branch, rev);
             return rev;
         } else {
@@ -701,7 +706,7 @@ const TaskBuild = new Lang.Class({
 
         this.ostreeRepo.prepare_transaction(cancellable);
         let file = this._writeMtreeFromDirectory(finalBuildResultDir, setuidFiles, cancellable);
-        let rev = this._commit(buildRef, "Build", file, cancellable);
+        let rev = this._commit(buildRef, "Build", file, cancellable, { withParent: false });
         this.ostreeRepo.commit_transaction(cancellable);
 
         let ostreeRevision = this._saveComponentBuild(buildRef, rev, expandedComponent, cancellable);