[DRE-maint] Bug#1135482: ruby-rubocop-ast: FTBFS: dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2

[Santiago Vila]

Package: src:ruby-rubocop-ast
Version: 1.49.1-1
Severity: serious
Tags: ftbfs forky sid

Dear maintainer:

During a rebuild of all packages in unstable, this package failed to build.

Below you will find the last part of the build log (probably the most
relevant part, but not necessarily). If required, the full build log
is available here:

https://people.debian.org/~sanvila/build-logs/202605/

About the archive rebuild: The build was made on virtual machines from AWS,
using sbuild and a reduced chroot with only build-essential packages.

If you cannot reproduce the bug please contact me privately, as I
am willing to provide ssh access to a virtual machine where the bug is
fully reproducible.

If this is really a bug in one of the build-depends, please use
reassign and add an affects on src:ruby-rubocop-ast, so that this is still
visible in the BTS web page for this package.

Thanks.

--------------------------------------------------------------------------------
[...]
 debian/rules clean
dh clean --buildsystem=ruby --with ruby
   dh_auto_clean -O--buildsystem=ruby
	dh_ruby --clean
   dh_autoreconf_clean -O--buildsystem=ruby
   dh_clean -O--buildsystem=ruby
 debian/rules binary
dh binary --buildsystem=ruby --with ruby
   dh_update_autotools_config -O--buildsystem=ruby
   dh_autoreconf -O--buildsystem=ruby
   dh_auto_configure -O--buildsystem=ruby
	dh_ruby --configure
   debian/rules override_dh_auto_build
make[1]: Entering directory '/<<PKGBUILDDIR>>'
rake -f tasks/compile.rake generate
rake aborted!
NameError: uninitialized constant Rake::TaskManager::Pathname (NameError)

        when Pathname
             ^^^^^^^^
/usr/share/rubygems-integration/all/gems/rake-13.4.2/exe/rake:27:in `<top (required)>'
Tasks: TOP => generate => generate:lexer
(See full trace by running task with --trace)
make[1]: *** [debian/rules:13: override_dh_auto_build] Error 1
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:7: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2
--------------------------------------------------------------------------------