Avoid assertion violations in 'back_to_previous_visible_line_start'

* src/xdisp.c (back_to_previous_visible_line_start): Avoid
assertion violations when narrowed_begv is in effect.

diff --git a/src/xdisp.c b/src/xdisp.c
index 84203f0ed0c95137b4ee69a84b63dad55932b710..ac76917eb3fceb0ef780c86f9bb38491b8a794af 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -7226,7 +7226,8 @@ back_to_previous_visible_line_start (struct it *it)
   it->continuation_lines_width = 0;
 
   eassert (IT_CHARPOS (*it) >= BEGV);
-  eassert (IT_CHARPOS (*it) == BEGV
+  eassert (it->narrowed_begv > BEGV
+          || IT_CHARPOS (*it) == BEGV
           || FETCH_BYTE (IT_BYTEPOS (*it) - 1) == '\n');
   CHECK_IT (it);
 }