Comment 3 for bug 1636931

As far as snapd is concerned, this was never broken since it was originally created. The problem is always something out-of-date: snapd, snap-confine, or the ubuntu-core snap.

For the record, I just went through the process of installing snapd 2.20 from edge, and ubuntu-core from edge, and it all works fine:

[niemeyer@nomade ..s/snapctl-hooks]% snap --version
snap 2.20
snapd 2.20
series 16
ubuntu 16.04

[niemeyer@nomade ..s/snapctl-hooks]% dpkg -l snapd snap-confine
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-====================================-=======================-=======================-=============================================================================
ii snap-confine 2.20 amd64 Support executable to apply confinement for snappy apps
ii snapd 2.20 amd64 Tool to interact with Ubuntu Core Snappy.

[niemeyer@nomade ..s/snapctl-hooks]% snap list ubuntu-core
Name Version Rev Developer Notes
ubuntu-core 16.04.1 1239 canonical -

Test snap:

[niemeyer@nomade ..s/snapctl-hooks]% sudo snap install ./snapctl-hooks_1.0_all.snap --dangerous
[sudo] password for niemeyer:
snapctl-hooks 1.0 installed

[niemeyer@nomade ..s/snapctl-hooks]% sudo snap set snapctl-hooks command=test-snapctl-set-foo

[niemeyer@nomade ..s/snapctl-hooks]% sudo snap get snapctl-hooks foo
bar

Different snap, created by snapcraft:

[niemeyer@nomade ..s/snapctl-hooks]% snap changes hello
ID Status Spawn Ready Summary
381 Done 2016-12-16T17:44:35Z 2016-12-16T17:44:36Z Install "hello" snap from file "./hello_1.0_amd64.snap"
382 Done 2016-12-16T17:45:11Z 2016-12-16T17:45:11Z Change configuration of "hello" snap

[niemeyer@nomade ..s/snapctl-hooks]% snap change 382
Status Spawn Ready Summary
Done 2016-12-16T17:45:11Z 2016-12-16T17:45:11Z Run configure hook of "hello" snap