Reset change bar information when breaking row

This is a much less invasive version of da2696cc+da2696cc, which
reduces the risk to a minimum. There may be other Row members that
need resetting, we'll see that later.

Fixes bug #11396.

src/TextMetrics.cpp

@@ -836,6 +836,7 @@ bool TextMetrics::breakRow(Row & row, int const right_margin) const
 	row.clear();
 	row.left_margin = leftMargin(row.pit(), pos);
 	row.right_margin = right_margin;
+	row.needsChangeBar(false);
 	if (is_rtl)
 		swap(row.left_margin, row.right_margin);
 	// Remember that the row width takes into account the left_margin

status.23x

@@ -213,6 +213,10 @@ What's new
 - Get rid of spurious empty entry in list of equations when creating new
   formula (bug 11423).
 
+- Handle some cases where the change bar in the margin did not get updated 
+  (bug 11396).
+
+
 
 * INTERNALS