I was trying to upgrade my Proxmox machine tonight (just a routine thing, literally ran apt-get update and apt-get upgrade) and everything worked except I got this error. I followed some forum post instructions by running apt-get dist-upgrade, but I can't seem to fix these loops. Help?
Never mind.
Oddly enough, in my sleepy stupor, I was reading through some errors and noticed it said that zfs-mount was required before zfs-mount could be started. That made me think that maybe earlier when I followed the age-old Proxmox ZFS workaround, which partially consists of adding "zfs-mount" to the "$local_fs" line in insserv.conf, I made it try to run a service twice. Looking back on myself in my sleepy stupor, I'm still not 100% sure what I was thinking in trying this, but I did. I removed the "zfs-mount" line from my insserv.conf file. Upon doing that, it fixed everything. I don't know exactly why, but I know after multiple apt-get update/apt-get upgrade and reboots, it works fine, no package errors or anything, and I can get to my VM images in my ZFS pool.
I have no idea why that worked, but it did. So hopefully my 2AM findings save someone else the trouble. If you have questions let me know, I'll be happy to post files so we can compare and figure out why the heck it does this in the first place.