[DRE-maint] Bug#839567: rake does not work with jruby

[Helmut Grohne]

Package: rake,jruby
Severity: serious
Justification: policy 3.5
User: helmutg at debian.org
Usertags: rebootstrap

Hi,

Please consider the following interaction with a fresh sid chroot:

# apt-get install -y --no-install-recommends jruby
...
# apt-get install --no-install-recommends rake
# rake
-bash: /usr/bin/rake: /usr/bin/ruby: bad interpreter: No such file or directory
#

rake declares a dependency on ruby | ruby-interpreter. jruby declares
that it provides ruby-interpreter. It seems that rake expects
/usr/bin/ruby to be available, but jruby does not contain such a file
nor has a maintainer script that would create one (via alternatives or
other means).

Thus this looks like a broken contract on the meaning of
ruby-interpreter. I believe we have the following options to move
forward:

1. rake removes the ruby-interpreter alternative acknowledging that
   ruby-interpreter does not mean to include /usr/bin/ruby.
2. jruby removes the provides on ruby-interpreter acknowledging that
   ruby-interpreter should provide /usr/bin/ruby.
3. jruby instantiates /usr/bin/ruby as it is required for providing
   ruby-interpreter.

This bug was found by inspecting a valid installation set for ruby:i386
on an amd64 system generated by dose3. Choosing option 1 or 2 will mean
that ruby stops being installable for foreign architectures unless rake
annotates its ruby dependency with :any (ruby is m-a:allowed already).

Helmut