Named Collections IDs Are Used in Reverse Order

Before you submit bug reports: https://vdirsyncer.pimutils.org/en/stable/contributing.html

Things to include in your bugreport:

• vdirsyncer version: 0.18.0
• Your Python version: 3.9.2
• Your operating system: Debian Stretch
• Config file:

[general]
status_path = "/home/vdirsyncer/status/"

[storage localCards]
type = "filesystem"
path = "/home/vdirsyncer/contacts/"
fileext = ".vcf"

[storage iCloud]
type = "carddav"
url = "https://contacts.icloud.com/"
username = "example@example.com"
password = "secret"

[pair iCloudAndLocalCards]
a = "iCloud"
b = "localCards"
collections = [["All iCloud Contacts",, "alliCloudContacts", "very-long-uuid"]]

If I run

/home/vdirsyncer/.local/bin/vdirsyncer -v DEBUG -c vdirsyncer.ini  discover iCloudAndLocalCards

the output is

localCards:
warning: No collection "alliCloudContacts"" found for storage iCloud.
Should vdirsyncer attempt to create it? [y/N]:

According to the docs http://vdirsyncer.pimutils.org/en/stable/config.html#pair-section
the format is the following ["config_name", "name_a", "name_b"] but it actually parses it like
["config_name", "name_b", "name_a"]

Am I missing something?

Start by reproducing the documented pair-section configuration with the vdirsyncer 0.18.0 discover command and compare the documented ["config_name", "name_a", "name_b"] order with the observed output. Trace the configuration parsing and collection lookup; done means the documented order and actual parsing agree.