git: b3f23ae1e22b - stable/13 - nextboot: Reimplement missing -a option

The branch stable/13 has been updated by des:

URL: https://cgit.FreeBSD.org/src/commit/?id=b3f23ae1e22bf88de5ec09c524e7e0beb16b5c76

commit b3f23ae1e22bf88de5ec09c524e7e0beb16b5c76
Author:     Dag-Erling Smørgrav <des@FreeBSD.org>
AuthorDate: 2025-12-13 22:46:25 +0000
Commit:     Dag-Erling Smørgrav <des@FreeBSD.org>
CommitDate: 2026-02-05 15:01:12 +0000

    nextboot: Reimplement missing -a option
    
    PR:             260520
    MFC after:      3 days
    Fixes:          e307eb94ae52 ("loader: zfs should support bootonce an nextboot")
    
    (cherry picked from commit 33510b16e663bde5be5e4a56ccb17f848c41ef4e)
---
 sbin/reboot/nextboot.sh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sbin/reboot/nextboot.sh b/sbin/reboot/nextboot.sh
index 4b34001677ff..d68c865da4e5 100644
--- a/sbin/reboot/nextboot.sh
+++ b/sbin/reboot/nextboot.sh
@@ -115,6 +115,10 @@ set -e
 
 nextboot_tmp=$(mktemp $(dirname ${nextboot_file})/nextboot.XXXXXX)
 
+if [ ${append} = "YES" -a -f ${nextboot_file} ]; then
+	cp -f ${nextboot_file} ${nextboot_tmp}
+fi
+
 if [ -n "${zfs}" ]; then
 	zfsbootcfg -z ${zfs} -n freebsd:nvstore -k nextboot_enable -v YES
 	cat >> ${nextboot_tmp} << EOF