Well, I guess this error happens (umount: /tmp/zfsmnt.5DJ7yi: target is busy.) because there is another thing mounted inside of it (/tmp/zfsmnt.5DJ7yi/boot) as mentioned in the end of the bug description.
I guess these commands are coming from grub2/debian/patches/ubuntu-zfs-enhance-support.patch?
Well, I guess this error happens (umount: /tmp/zfsmnt.5DJ7yi: target is busy.) because there is another thing mounted inside of it (/tmp/zfsmnt. 5DJ7yi/ boot) as mentioned in the end of the bug description.
I guess these commands are coming from grub2/debian/ patches/ ubuntu- zfs-enhance- support. patch?
I'm not sure who (what team) owns it.