--- ./apt.old	2009-04-08 12:12:46.000000000 -0300
+++ ./apt	2009-04-08 13:04:02.000000000 -0300
@@ -49,8 +49,18 @@
         return 0
     fi
 
+    # Due to some timezones returning 'invalid date' for the start of DST
+    # (eg America/Sao_Paulo), if the file has an invalid date, remove the stamp
+    # file and return 0. See coreutils bug:
+    # http://lists.gnu.org/archive/html/bug-coreutils/2007-09/msg00176.html
+    stamp_date=$(date -r $stamp --iso-8601)
+    if [ "$?" != "0" ]; then
+        rm -f $stamp
+        return 0
+    fi
+
     # compare midnight today to midnight the day the stamp was updated
-    stamp=$(date --date=$(date -r $stamp --iso-8601) +%s)
+    stamp=$(date --date=$stamp_date +%s)
     now=$(date --date=$(date --iso-8601) +%s)
     delta=$(($now-$stamp))