[DRE-maint] Bug#920031: schleuder: DEP8 failures with ruby-mail 2.7.1

[Andreas Hasenack]

Package: schleuder
Version: 2.7.1+dfsg1-1
Severity: normal

Dear Maintainer,

The DEP8 tests from schleuder are currently failing on all arches
because it can't find ruby-mail 2.6.0:

https://ci.debian.net/packages/s/schleuder/

The test output doesn't show it, but here is a manual run in an Ubuntu
Disco LXD container:

https://pastebin.ubuntu.com/p/Tp3g2PFPp7/
...
/usr/lib/ruby/2.5.0/rubygems/dependency.rb:312:in `to_specs': Could
not find 'mail' (~> 2.6.0) - did find: [mail-2.7.1]
(Gem::MissingSpecVersionError)

I found these upstream:
- https://0xacab.org/schleuder/schleuder/merge_requests/128/diffs:
commit that pinned ruby-mail to 2.6.0
- https://0xacab.org/schleuder/schleuder/issues/277: "ruby-mail 2.7.0
breaks unicode and various other formats
"

I hacked the gem spec to allow ruby-mail 2.7.1, which is what we have
in Ubuntu Disco and Debian Testing, and the test run had two failures:

https://pastebin.ubuntu.com/p/WZhZf42gJg/
...

Failures:

  1) user sends keyword x-resend with utf-8 body and umlauts
     Failure/Error:
expect(message.parts[1].body.to_s.force_encoding(message.parts[1].charset)).to
eql(content_body.encode(message.parts[1].charset))

       expected: "This is a test\nAnd here are some umlauts:ÄäÖöÜüß"
            got: "This is a test\r\nAnd here are some umlauts:ÄäÖöÜüß"

       (compared using eql?)

       Diff:

     # ./spec/schleuder/integration/keywords_spec.rb:1923:in `block (2
levels) in <top (required)>'
     # ./spec/spec_helper.rb:47:in `block (3 levels) in <top (required)>'
     # ./spec/spec_helper.rb:46:in `block (2 levels) in <top (required)>'

  2) user sends keyword x-resend with iso-8859-1 body
     Failure/Error:
expect(message.parts[1].body.to_s.force_encoding(message.parts[1].charset)).to
eql(content_body.encode(message.parts[1].charset))

       expected: "Hello again! \xA1Hola!\n"
            got: "Hello again! \xA1Hola!\r\n"

       (compared using eql?)

       Diff:

     # ./spec/schleuder/integration/keywords_spec.rb:1881:in `block (2
levels) in <top (required)>'
     # ./spec/spec_helper.rb:47:in `block (3 levels) in <top (required)>'
     # ./spec/spec_helper.rb:46:in `block (2 levels) in <top (required)>'