[DRE-maint] Bug#888120: ruby-dalli: FTBFS on ruby2.5: "File does not exist:"

[Chris West (Faux)]

Source: ruby-dalli
Version: 2.7.4-1
Severity: important
User: debian-ruby at lists.debian.org
Usertags: ruby2.5

Dear Maintainer,

This package fails to build against ruby2.5. Soon, there will
be a transition to ruby2.5, and this package will FTBFS in sid.

There may be some details on the wiki about common problems:
https://wiki.debian.org/Teams/Ruby/Ruby25Transition

I have no idea what's going on here, maybe a gem2deb problem causing it
to not be happy building twice in a row?

Build log excerpt:

...

Finished in 13.066640s, 0.0765 runs/s, 0.0765 assertions/s.

1 runs, 1 assertions, 0 failures, 0 errors, 0 skips
/usr/bin/ruby2.5 /usr/bin/gem2deb-test-runner

┌──────────────────────────────────────────────────────────────────────────────┐
│ Checking Rubygems dependency resolution on ruby2.5                           │
└──────────────────────────────────────────────────────────────────────────────┘

GEM_PATH=debian/ruby-dalli/usr/share/rubygems-integration/all:/root/.gem/ruby/2.5.0:/var/lib/gems/2.5.0:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.5.0:/usr/share/rubygems-integration/2.5.0:/usr/share/rubygems-integration/all ruby2.5 -e gem\ \"dalli\"

┌──────────────────────────────────────────────────────────────────────────────┐
│ Run tests for ruby2.5 from debian/ruby-tests.rake                            │
└──────────────────────────────────────────────────────────────────────────────┘

RUBYLIB=/build/ruby-dalli-2.7.4/debian/ruby-dalli/usr/lib/ruby/vendor_ruby:. GEM_PATH=debian/ruby-dalli/usr/share/rubygems-integration/all:/root/.gem/ruby/2.5.0:/var/lib/gems/2.5.0:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.5.0:/usr/share/rubygems-integration/2.5.0:/usr/share/rubygems-integration/all ruby2.5 -S rake -f debian/ruby-tests.rake
/usr/bin/ruby2.5 -w -I"test"  "/usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb" "test/benchmark_test.rb" -v
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: already initialized constant WANT_RAILS_VERSION
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: previous definition of WANT_RAILS_VERSION was here
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: already initialized constant WANT_RAILS_VERSION
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: previous definition of WANT_RAILS_VERSION was here
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: already initialized constant WANT_RAILS_VERSION
/build/ruby-dalli-2.7.4/test/helper.rb:13: warning: previous definition of WANT_RAILS_VERSION was here

File does not exist: 

rake aborted!
Command failed with status (1): [ruby -w -I"test"  "/usr/lib/ruby/vendor_ruby/rake/rake_test_loader.rb" "test/benchmark_test.rb" -v]

Tasks: TOP => default
(See full trace by running task with --trace)
ERROR: Test "ruby2.5" failed. Exiting.
dh_auto_install: dh_ruby --install /build/ruby-dalli-2.7.4/debian/ruby-dalli returned exit code 1
debian/rules:6: recipe for target 'binary' failed
make: *** [binary] Error 1
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2

Full build log:
https://rbuild.fau.xxx/2018-01-23/ruby-dalli.log


Please fix it!

Cheers,
Chris.