Add an explicit exit 0 to the end of the script.

The implicit return is "$?", which can be set non-zero by
an earlier command.

src/zfs-auto-snapshot.sh

@@ -136,7 +136,7 @@ GETOPT=$(getopt \
   --longoptions=default-exclude,dry-run,skip-scrub,recursive \
   --longoptions=keep:,label:,prefix:,sep: \
   --longoptions=debug,help,quiet,syslog,verbose \
-  --options=dnshl:k:rs:gv \
+  --options=dnshl:k:rs:qgv \
   -- "$@" ) \
   || exit 1
 
@@ -508,4 +508,5 @@ done
 print_log notice "@$SNAPSHOT_NAME, \
 $SNAPSHOT_COUNT created, $DESTRUCTION_COUNT destroyed, $WARNING_COUNT warnings."
 
+exit 0
 # }