New issue by ahesford on void-packages repository

https://github.com/void-linux/void-packages/issues/20711

Description:
I'm creating this issue to document and track a potential incompatibility between `zfs-0.8.3_2`, `linux5.5` and encryption. On the `#voidlinux` IRC channel, user `w1kl4s` reported that a system with an unencrypted boot partition and an encrypted root fails to boot `linux5.5` with `zfs-0.8.3_2` and `zfsbootmenu`, although the same problem reportedly affects a system using `rEFInd` without `zfsbootmenu`.

@zdykstra may be able to reproduce this issue and provide more insight. I do not use encyrption with ZFS but have no issues booting current `linux5.4`, `linux5.5` or `linux5.6` kernels using `zfs-0.8.3_2`.

Note that ZFS 0.8.3 does not officially support any kernel above Linux 5.4. The patch applied in Void package `zfs-0.8.3_2` to support `linux5.6` is a backport of patches accepted upstream to support Linux 5.6 (the patch file in the tree references the upstream issue) while we wait for a new ZFS point release or OpenZFS 2.0.

Hopefully, we can reproduce the issue and determine whether this problem appears upstream or only in the backported patch.