[gnome-boxes] SnapshotListRow: Unset the activity correctly

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit d6fb7484c04f899d232d8a2dd2640211661443ad
Author: Timm Bäder <mail baedert org>
Date:   Fri Aug 29 21:51:44 2014 +0200

    SnapshotListRow: Unset the activity correctly
    
    When we're done reverting, we need to set the activity_message to null
    and not to "", otherwise the SnapshotsProperty will simply use "" as the
    new activity message.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=735678

 src/snapshot-list-row.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/snapshot-list-row.vala b/src/snapshot-list-row.vala
index bbe3011..884e42f 100644
--- a/src/snapshot-list-row.vala
+++ b/src/snapshot-list-row.vala
@@ -163,7 +163,7 @@ private class Boxes.SnapshotListRow : Gtk.ListBoxRow {
                 machine.window.notificationbar.display_error (_("Failed to apply snapshot"));
             }
             if (show_activity)
-                activity_message = "";
+                activity_message = null;
         });
     }