[DRE-maint] Bug#795042: ruby-gnuplot: FTBFS: test_gnuplot.rb:97: uninitialized constant Config (NameError)

[Chris West (Faux)]

Source: ruby-gnuplot
Version: 2.6.2-1
Severity: serious
Justification: fails to build from source
Tags: sid stretch
User: reproducible-builds at lists.alioth.debian.org
Usertags: ftbfs
X-Debbugs-CC: reproducible-builds at lists.alioth.debian.org

Dear Maintainer,

The package fails to build:

┌──────────────────────────────────────────────────────────────────────────────┐
│ Run tests for ruby2.2 from debian/ruby-test-files.yaml                       │
└──────────────────────────────────────────────────────────────────────────────┘

RUBYLIB=/ruby-gnuplot-2.6.2/debian/ruby-gnuplot/usr/lib/ruby/vendor_ruby:. ruby2.2 -ryaml -e YAML.load_file\(\"debian/ruby-test-files.yaml\"\).each\ \{\ \|f\|\ require\ f\ \}
created sin_wave.gif
/ruby-gnuplot-2.6.2/test/test_gnuplot.rb:97:in `<top (required)>': uninitialized constant Config (NameError)
	from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	from /usr/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	from -e:1:in `block in <main>'
	from -e:1:in `each'
	from -e:1:in `<main>'
ERROR: Test "ruby2.2" failed. Exiting.

Full build log:
https://reproducible.debian.net/rb-pkg/unstable/amd64/ruby-gnuplot.html

-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.19.0-23-generic (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)