Don't retrace if there are no lines to draw.

In this case, things go funny because the ANSI escape
sequence ^[[0A will still go up one line, in spite
of the zero.

1 files changed, 1 insertions, 1 deletions

diff --git a/pw.c b/pw.c
index 5d5c5b9..6538cbd 100644
--- a/pw.c
+++ b/pw.c
@@ -446,7 +446,7 @@ static unsigned redraw(char **circbuf, int nlines, unsigned hpos, unsigned hist,
   if ((stat & stat_bkgnd))
     return stat;
 
-  if (updln) {
+  if (updln && snaplines[hist] > 0) {
     printf("\r\033[%dA", snaplines[hist]);
     if ((stat & stat_lino) == 0) {
       for (int i = 0; i < snaplines[hist]; i++)