[LyX/2.1.x] Fix bug in get_containing_inset and get_containing_layout

[Juergen Spitzmueller]

commit e52b85d2671881b3043e9062a32ef32b4c995e41
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Fri Feb 13 16:28:00 2015 +0100

    Fix bug in get_containing_inset and get_containing_layout
    
    We have to check if this is really a parent (or just the first inset/layout 
we have).

diff --git a/lib/lyx2lyx/parser_tools.py b/lib/lyx2lyx/parser_tools.py
index f5f285e..2b6ae05 100644
--- a/lib/lyx2lyx/parser_tools.py
+++ b/lib/lyx2lyx/parser_tools.py
@@ -438,7 +438,10 @@ def get_containing_inset(lines, i):
       if endins > j:
           break
       j = stins - 1
-  
+
+  if endins < i:
+      return False
+
   inset = get_value(lines, "\\begin_inset", stins)
   if inset == "":
       # shouldn't happen
@@ -464,7 +467,10 @@ def get_containing_layout(lines, i):
       if endlay > i:
           break
       j = stlay - 1
-  
+
+  if endlay < i:
+      return False
+
   lay = get_value(lines, "\\begin_layout", stlay)
   if lay == "":
       # shouldn't happen