Comment 14 for bug 1871981

I hit this bug today while doing charm upgrades.
The upgrade path is 19.07->19.10->20.02->20.05.
However, the bugfix is only released to 20.05.
I tried to cherry-pick it to 19.07 and it conflicts.
So we cancelled the charm upgrade.
It will be very helpful if we can have backports for bugfix like this.