[LyX/2.2.x] lyx2lyx/lyx_2_2.py: backport another box reversion issue

[Uwe Stöhr]

commit 62ad4a1ab5ff5f4daf4ea19ec56f6a176598d4f3
Author: Uwe Stöhr <uwesto...@lyx.org>
Date:   Mon Apr 24 23:02:09 2017 +0200

    lyx2lyx/lyx_2_2.py: backport another box reversion issue
---
 lib/lyx2lyx/lyx_2_2.py |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/lyx2lyx/lyx_2_2.py b/lib/lyx2lyx/lyx_2_2.py
index c30477d..a65f8ca 100644
--- a/lib/lyx2lyx/lyx_2_2.py
+++ b/lib/lyx2lyx/lyx_2_2.py
@@ -1093,11 +1093,13 @@ def revert_BoxFeatures(document):
         if i == -1:
             return
         binset = find_token(document.body, "\\begin_inset Box", i - 11)
-        if binset == -1:
-            return # then "thickness" is is just a word in the text
+        if binset == -1 or binset != i - 11:
+            i = i + 1
+            continue # then "thickness" is is just a word in the text
         einset = find_end_of_inset(document.body, binset)
         if einset == -1:
             document.warning("Malformed LyX document: Can't find end of box 
inset!")
+            i = i + 1
             continue
         # read out the values
         beg = document.body[i].find('"');