[DRE-maint] Bug#797257: ruby-rack-protection: FTBFS: `block in expect_with': :stdlib is not supported (ArgumentError)

[Chris West (Faux)]

Source: ruby-rack-protection
Version: 1.5.2-1
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 ruby2.1 from debian/ruby-tests.rake                            │
└──────────────────────────────────────────────────────────────────────────────┘

RUBYLIB=/ruby-rack-protection-1.5.2/debian/ruby-rack-protection/usr/lib/ruby/vendor_ruby:. rake2.1 -f debian/ruby-tests.rake
/usr/bin/ruby2.1 /usr/bin/rspec --pattern spec/\*\*\{,/\*/\*\*\}/\*_spec.rb
/usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:656:in `block in expect_with': :stdlib is not supported (ArgumentError)
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:635:in `map'
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:635:in `expect_with'
	from /ruby-rack-protection-1.5.2/spec/spec_helper.rb:96:in `block in <top (required)>'
	from /usr/lib/ruby/vendor_ruby/rspec/core.rb:97:in `configure'
	from /ruby-rack-protection-1.5.2/spec/spec_helper.rb:95:in `<top (required)>'
	from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /ruby-rack-protection-1.5.2/spec/authenticity_token_spec.rb:1:in `<top (required)>'
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:1327:in `load'
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:1327:in `block in load_spec_files'
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:1325:in `each'
	from /usr/lib/ruby/vendor_ruby/rspec/core/configuration.rb:1325:in `load_spec_files'
	from /usr/lib/ruby/vendor_ruby/rspec/core/runner.rb:103:in `setup'
	from /usr/lib/ruby/vendor_ruby/rspec/core/runner.rb:89:in `run'
	from /usr/lib/ruby/vendor_ruby/rspec/core/runner.rb:74:in `run'
	from /usr/lib/ruby/vendor_ruby/rspec/core/runner.rb:42:in `invoke'
	from /usr/bin/rspec:4:in `<main>'
/usr/bin/ruby2.1 /usr/bin/rspec --pattern spec/\*\*\{,/\*/\*\*\}/\*_spec.rb failed
ERROR: Test "ruby2.1" failed. Exiting.

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

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