Prevent GPG >= 2.1 from using .kbx pubring format during import

[echtish]

As described here[1], if pubring.gpg already exists, .kbx format will not be used. This fixes tests for new GPG versions that otherwise failed due to pubring.gpg not existing after gpg --import into $TMP/gpg.

1: https://www.gnupg.org/faq/whats-new-in-2.1.html

Without this commit:

$ cat /etc/os-release
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
ID_LIKE=archlinux
ANSI_COLOR="0;36"
HOME_URL="https://www.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://bugs.archlinux.org/"
$ gpg --version
gpg (GnuPG) 2.1.17
$ git log -n 1
commit 4f412fa6daded0cac6b8f9b4f5c643343a9cb36f
Author: Stephen Ryan <ryaner@users.noreply.github.com>
Date:   Tue Nov 22 09:19:21 2016 +0000

    Let install-man task work on second and subsequent attempts

    gzip would previously fail due to the existing man pages

    Fixes GH-44
$ make check
git clone --depth 1 https://github.com/sstephenson/bats.git test/tmp/bats
Cloning into 'test/tmp/bats'...
remote: Counting objects: 61, done.
remote: Compressing objects: 100% (48/48), done.
remote: Total 61 (delta 0), reused 45 (delta 0), pack-reused 0
Unpacking objects: 100% (61/61), done.
git clone --depth 1 https://github.com/jasonkarns/bats-assert.git test/tmp/bats-assert
Cloning into 'test/tmp/bats-assert'...
remote: Counting objects: 24, done.
remote: Compressing objects: 100% (19/19), done.
remote: Total 24 (delta 7), reused 13 (delta 4), pack-reused 0
Unpacking objects: 100% (24/24), done.
mkdir -p test/tmp/bin
ln -sf $(which dash) test/tmp/bin/sh
PATH=test/tmp/bin/:$PATH test/tmp/bats/bin/bats test/
 ✗ freight-add adds package to distro main component
   (from function `gpg_init' in file test/freight_helpers.bash, line 45,
    from function `freight_init' in file test/freight_helpers.bash, line 17,
    from function `setup' in test file test/apt_add.bats, line 6)
     `freight_init' failed with status 2
   gpg: keybox '/home/jeremy/src/freight-team/test/tmp/gpg/pubring.kbx' created
   gpg: agent_genkey failed: Operation cancelled
   gpg: key generation failed: Operation cancelled
 ✓ freight-add adds package to a component
 ✓ freight-add adds package and hard link to multiple components
 ✓ freight-add detects duplicate package
 ✓ freight-add adds source .dsc files
 ✓ freight-add adds source .tar.gz files
 ✓ freight-add adds source .orig.tar.gz files
 ✓ freight-add handles VARLIB being a symlink
 ✗ freight-cache builds distro Release file
   (from function `freight_cache' in file test/freight_helpers.bash, line 33,
    in test file test/apt_cache.bats, line 14)
     `freight_cache -v' failed
   # [freight] added /home/jeremy/src/freight-team/test/fixtures/test_1.0_all.deb to apt/example
   # [freight] added /home/jeremy/src/freight-team/test/fixtures/test_1.0_all.deb to apt/example/comp
   # [freight] adding test_1.0_all.deb to pool
   # [freight] adding test_1.0_all.deb to pool
   gpg: skipped "freight@example.com": No secret key
   gpg: signing failed: No secret key
   # [freight] couldn't sign the repository, perhaps you need to run
   # [freight] gpg --gen-key and update the GPG setting in /home/jeremy/src/freight-team/test/tmp/freight/etc/freight.conf
   # [freight] (see freight(5) for more information)

With it:

$ make check
ln -sf $(which dash) test/tmp/bin/sh
PATH=test/tmp/bin/:$PATH test/tmp/bats/bin/bats test/
 ✓ freight-add adds package to distro main component
 ✓ freight-add adds package to a component
 ✓ freight-add adds package and hard link to multiple components
 ✓ freight-add detects duplicate package
 ✓ freight-add adds source .dsc files
 ✓ freight-add adds source .tar.gz files
 ✓ freight-add adds source .orig.tar.gz files
 ✓ freight-add handles VARLIB being a symlink
 ✓ freight-cache builds distro Release file
 ✓ freight-cache builds per-component Release file
 ✓ freight-cache builds pool
 ✓ freight-cache generates valid Release.gpg signature
 ✓ freight-cache signs Release.gpg with two keys
 ✓ freight-cache works without tty
 - apt-get fetches package list (skipped: missing apt-get)
 ✓ freight-cache removes deleted packages from pool
 ✓ freight-cache --keep retains deleted packages in pool
 ✓ freight-cache handles VARLIB being a symlink
 ✓ freight-cache skips partial source packages
 ✓ freight-cache builds source-only archive
 - apt-get fetches source package list (skipped: missing apt-get)

Tested on debian:

$ sudo make clean
rm -rf *.deb deb man/man*/*.html test/tmp
find . -name '*~' -delete
$ git log --pretty=oneline --abbrev-commit -n 1
1c9b5a2 Prevent GPG >= 2.1 from using .kbx pubring format
$ docker run -it -v $(pwd):/freight debian:stable /bin/bash -c 'apt-get update &>/dev/null; apt-get install --no-install-recommends -y git make ca-certificates &>/dev/null; cd /freight && make check'
git clone --depth 1 https://github.com/sstephenson/bats.git test/tmp/bats
Cloning into 'test/tmp/bats'...
remote: Counting objects: 61, done.
remote: Compressing objects: 100% (48/48), done.
remote: Total 61 (delta 0), reused 45 (delta 0), pack-reused 0
Unpacking objects: 100% (61/61), done.
Checking connectivity... done.
git clone --depth 1 https://github.com/jasonkarns/bats-assert.git test/tmp/bats-assert
Cloning into 'test/tmp/bats-assert'...
remote: Counting objects: 24, done.
remote: Compressing objects: 100% (19/19), done.
remote: Total 24 (delta 7), reused 13 (delta 4), pack-reused 0
Unpacking objects: 100% (24/24), done.
Checking connectivity... done.
mkdir -p test/tmp/bin
ln -sf $(which dash) test/tmp/bin/sh
PATH=test/tmp/bin/:$PATH test/tmp/bats/bin/bats test/
 ✓ freight-add adds package to distro main component
 ✓ freight-add adds package to a component
 ✓ freight-add adds package and hard link to multiple components
 ✓ freight-add detects duplicate package
 ✓ freight-add adds source .dsc files
 ✓ freight-add adds source .tar.gz files
 ✓ freight-add adds source .orig.tar.gz files
 ✓ freight-add handles VARLIB being a symlink
 ✓ freight-cache builds distro Release file
 ✓ freight-cache builds per-component Release file
 ✓ freight-cache builds pool
 ✓ freight-cache generates valid Release.gpg signature
 ✓ freight-cache signs Release.gpg with two keys
 ✓ freight-cache works without tty
 ✓ apt-get fetches package list
 ✓ freight-cache removes deleted packages from pool
 ✓ freight-cache --keep retains deleted packages in pool
 ✓ freight-cache handles VARLIB being a symlink
 ✓ freight-cache skips partial source packages
 ✓ freight-cache builds source-only archive
 ✓ apt-get fetches source package list

21 tests, 0 failures

[mmoll]

merged, thanks @echtish!