Remove override files first

config/debian/dinstall.functions

@@ -287,6 +287,7 @@ function copyoverrides() {
 
     (
         shopt -s nullglob
+        rm -f ${indices}/override.*.gz
         for ofile in ${overridedir}/override.{wheezy,jessie,stretch,buster,sid}.{,extra.}{main,contrib,non-free}*; do
             bname=${ofile##*/}
             gzip -9cv --rsyncable  --no-name ${ofile} > ${indices}/${bname}.gz