[gitg] Reset head tree cache

[Jesse van den Kieboom <jessevdk src gnome org>]

commit 2904a3892824fcb9ab3b8a5b63932e56b4fdad60
Author: Jesse van den Kieboom <jessevdk gnome org>
Date:   Wed Jun 25 14:50:41 2014 +0200

    Reset head tree cache
    
    https://bugzilla.gnome.org/show_bug.cgi?id=728208

 libgitg/gitg-stage.vala |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/libgitg/gitg-stage.vala b/libgitg/gitg-stage.vala
index 1715b7c..18a4ebb 100644
--- a/libgitg/gitg-stage.vala
+++ b/libgitg/gitg-stage.vala
@@ -103,6 +103,8 @@ public class Stage : Object
 
        public async void refresh() throws Error
        {
+               d_head_tree = null;
+
                yield thread_index((index) => {
                        index.read(false);
                });
@@ -492,6 +494,8 @@ public class Stage : Object
                                } catch {}
                        }
 
+                       d_head_tree = null;
+
                        // run post commit
                        post_commit_hook(author);
                });