Ensure to sync repository to diff view

https://bugzilla.gnome.org/show_bug.cgi?id=768650

gitg/commit/gitg-commit.vala

@@ -1955,6 +1955,11 @@ namespace GitgCommit
 			                               d_main.button_discard,
 			                               "sensitive",
 			                               BindingFlags.DEFAULT);
+
+			application.bind_property("repository",
+			                          d_main.diff_view,
+			                          "repository",
+			                          BindingFlags.SYNC_CREATE);
 		}
 	}
 }

plugins/diff/gitg-diff.vala

@@ -32,12 +32,15 @@ namespace GitgDiff
 
 		private ulong d_selection_changed_id;
 
-		construct
+		protected override void constructed()
 		{
+			base.constructed();
+
 			d_diff = new Gitg.DiffView();
 
 			d_diff.show_parents = true;
-			d_diff.repository = application.repository;
+
+			application.bind_property("repository", d_diff, "repository", BindingFlags.SYNC_CREATE);
 
 			d_diff.show();