Bug#929929: Being unable to build with >= 4.19.38 is an RC

[Mo Zhou]

control: close -1

I made a big mistake. It's the ***LTS KERNEL UPDATE***
that breaks ZFS 0.7.12-2. It's not a ZFS bug at all!

An LTS KERNEL UPDATE that breaks stuff is where the
grave RC lies.

Bug#929929: Being unable to build with >= 4.19.38 is an RC

[Mo Zhou]

Source: zfs-linux
Version: 0.7.12-2
Severity: grave
Clarification: a foreseeable stable RC is grave enough.

Buster will be released with 4.19.37 kernel. That's fine
and it doesn't break ZFS. However, the changes introduced
in 4.19.38 and linux 5.0 break ZFS. That means the current
0.7.12-2 will fail to build everywhere after the first
Buster point release (with kernel version bump).
RC in stable is terrible enough.

We have two choices:
1. just unblock 0.7.13-1 .
2. revert diff(0.7.12-2,0.7.12-5), then cherry-pick
   the commits that fix the build issue, then go
   through t-p-u for 0.7.12-6 .

I dislike the second one but the first one seems hard
to achieve. Sigh.