Build error, chroot mount fails

[iTestAndroid]

Here is snippet from build log:

21:39:14 umount: /var/lib/jenkins/workspace/tem/pinebook1080p-build-49E3700jbW/rootfs/var: not mounted 21:39:14 + true 21:39:14 + umount /var/lib/jenkins/workspace/tem/pinebook1080p-build-49E3700jbW/rootfs 21:39:14 + echo OK 21:39:14 OK 21:39:14 + cp /usr/bin/qemu-aarch64-static /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/usr/bin 21:39:14 + cp /usr/bin/qemu-arm-static /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/usr/bin 21:39:14 + echo ':qemu-aarch64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-aarch64-static:F' 21:39:14 + cat 21:39:14 + chmod a+x /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/usr/sbin/policy-rc.d 21:39:14 + case $DISTRO in 21:39:14 + mv /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/etc/resolv.conf /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/etc/resolv.conf.bak 21:39:14 + cp /etc/resolv.conf /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/etc/resolv.conf 21:39:14 + DEB=ubuntu 21:39:14 + DEBUSER=pine64 21:39:14 + DEBUSERPW=pine64 21:39:14 + do_chroot apt-get -y update 21:39:14 + mount -o bind /tmp /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/tmp 21:39:14 + chroot /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs mount -t proc proc /proc 21:39:14 chroot: failed to run command 'mount': Exec format error 21:39:14 + cleanup 21:39:14 + '[' -e /var/lib/jenkins/workspace/tem/pinebook-build-3Rt4xvzLro/rootfs/proc/cmdline ']'

I added that echo thingy as it was marked as solution in another repo with similar issue, but it didn't help.