Comment 2 for bug 1817665

I was testing upstreams quick start example with the packages we have pre-tested in the PPA
=> https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/3668

Installing them is fine:
root@t:~# apt install python3-pymacaroons
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libfreetype6 os-prober
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
  libsodium18 python3-libnacl python3-six
The following NEW packages will be installed:
  libsodium18 python3-libnacl python3-pymacaroons python3-six
0 upgraded, 4 newly installed, 0 to remove and 13 not upgraded.
Need to get 174 kB of archives.
After this operation, 692 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://archive.ubuntu.com/ubuntu/ trusty-updates/main python3-six all 1.5.2-1ubuntu1.1 [8438 B]
Get:2 http://ppa.launchpad.net/ci-train-ppa-service/3668/ubuntu/ trusty/main libsodium18 amd64 1.0.8-5~ubuntu14.04.1 [145 kB]
Get:3 http://ppa.launchpad.net/ci-train-ppa-service/3668/ubuntu/ trusty/main python3-libnacl all 1.4.5-0ubuntu1~ubuntu14.04.1 [9662 B]
Get:4 http://ppa.launchpad.net/ci-train-ppa-service/3668/ubuntu/ trusty/main python3-pymacaroons all 0.9.2-0ubuntu1~ubuntu14.04.1 [10.1 kB]
Fetched 174 kB in 0s (606 kB/s)
Selecting previously unselected package libsodium18:amd64.
(Reading database ... 25108 files and directories currently installed.)
Preparing to unpack .../libsodium18_1.0.8-5~ubuntu14.04.1_amd64.deb ...
Unpacking libsodium18:amd64 (1.0.8-5~ubuntu14.04.1) ...
Selecting previously unselected package python3-libnacl.
Preparing to unpack .../python3-libnacl_1.4.5-0ubuntu1~ubuntu14.04.1_all.deb ...
Unpacking python3-libnacl (1.4.5-0ubuntu1~ubuntu14.04.1) ...
Selecting previously unselected package python3-six.
Preparing to unpack .../python3-six_1.5.2-1ubuntu1.1_all.deb ...
Unpacking python3-six (1.5.2-1ubuntu1.1) ...
Selecting previously unselected package python3-pymacaroons.
Preparing to unpack .../python3-pymacaroons_0.9.2-0ubuntu1~ubuntu14.04.1_all.deb ...
Unpacking python3-pymacaroons (0.9.2-0ubuntu1~ubuntu14.04.1) ...
Setting up libsodium18:amd64 (1.0.8-5~ubuntu14.04.1) ...
Setting up python3-libnacl (1.4.5-0ubuntu1~ubuntu14.04.1) ...
Setting up python3-six (1.5.2-1ubuntu1.1) ...
Setting up python3-pymacaroons (0.9.2-0ubuntu1~ubuntu14.04.1) ...
Processing triggers for libc-bin (2.19-0ubuntu6.14) ...

Then running the test against that...
root@t:~# python3 create.py
location cool-picture-service.example.com
identifier key-for-bob
cid picture_id = bobs_cool_cat.jpg
signature 83d8fa280b09938d3cffe045634f544ffaf712ff2c51ac34828ae8a42b277f8f
MDAyZWxvY2F0aW9uIGNvb2wtcGljdHVyZS1zZXJ2aWNlLmV4YW1wbGUuY29tCjAwMWJpZGVudGlmaWVyIGtleS1mb3ItYm9iCjAwMjdjaWQgcGljdHVyZV9pZCA9IGJvYnNfY29vbF9jYXQuanBnCjAwMmZzaWduYXR1cmUgg9j6KAsJk408_-BFY09UT_r3Ev8sUaw0goropCsnf48K
Sucessfully verified

Working fine, I attached the test script used with this comment ...