[easytag] Fix invariant check in ET_Undo_History_File_Data

[David King <davidk src gnome org>]

commit b4b3f6362182158414bdc1045e38e873f2eec424
Author: David King <amigadave amigadave com>
Date:   Mon Feb 11 17:36:59 2013 +0000

    Fix invariant check in ET_Undo_History_File_Data

 src/et_core.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/et_core.c b/src/et_core.c
index 76b51a9..6acc612 100644
--- a/src/et_core.c
+++ b/src/et_core.c
@@ -4316,7 +4316,7 @@ ET_File *ET_Undo_History_File_Data (void)
     ET_History_File *ETHistoryFile;
 
     g_return_val_if_fail (ETCore->ETHistoryFileList != NULL ||
-                          !ET_History_File_List_Has_Undo_Data (), NULL);
+                          ET_History_File_List_Has_Undo_Data (), NULL);
 
     ETHistoryFile = (ET_History_File *)ETCore->ETHistoryFileList->data;
     ETFile        = (ET_File *)ETHistoryFile->ETFile;