updated for version 7.2.345

Problem:    Tab line is not updated when the value of 'bt' is changed.
Solution:   Call redraw_titles(). (Lech Lorens)

src/option.c

@@ -6410,6 +6410,9 @@ did_set_string_option(opt_idx, varp, new_value_alloced, oldval, errbuf,
 	    }
 # endif
 	    curbuf->b_help = (curbuf->b_p_bt[0] == 'h');
+# ifdef FEAT_TITLE
+	    redraw_titles();
+# endif
 	}
     }
 #endif