dpl: Unable to activate net-ssh-gateway-2.0.0, because net-ssh-2.9.4 conflicts with net-ssh (>= 4.0.0)

I’m trying to run dpl in gitlab-ci. Some time ago (probably before August 2016, there was an update to rhc) I was able to use it without any problem, but seems that something has changed in the dependencies and is not working any more.

I’m using the official ruby 2.1 docker image.

gem install dpl
dpl --provider=openshift --user=a --password=b --domain=c --app=d --deployment_branch=master


Installing deploy dependencies
Successfully installed httpclient-2.4.0
1 gem installed
Successfully installed net-ssh-2.9.4
1 gem installed
Successfully installed net-ssh-4.1.0
Successfully installed net-scp-1.2.1
Successfully installed net-ssh-gateway-2.0.0
Successfully installed net-ssh-multi-1.2.1
The `minitar` executable is no longer bundled with `minitar`. If you are
expecting this executable, make sure you also install `minitar-cli`.
Successfully installed minitar-0.6.1
Successfully installed hashie-3.5.5
Successfully installed powerbar-1.0.18
Successfully installed minitar-cli-0.6.1
'archive-tar-minitar' has been deprecated; just install 'minitar'.
Successfully installed archive-tar-minitar-0.6.1
Successfully installed highline-1.6.21
Successfully installed commander-4.2.1
Successfully installed open4-1.3.4
===========================================================================

If this is your first time installing the RHC tools, please run 'rhc setup'

===========================================================================
Successfully installed rhc-1.38.7
13 gems installed
/usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:2288:in `raise_if_conflicts': Unable to activate net-ssh-gateway-2.0.0, because net-ssh-2.9.4 conflicts with net-ssh (>= 4.0.0) (Gem::ConflictError)
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1408:in `activate'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1442:in `block in activate_dependencies'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1428:in `each'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1428:in `activate_dependencies'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1410:in `activate'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1442:in `block in activate_dependencies'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1428:in `each'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1428:in `activate_dependencies'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/specification.rb:1410:in `activate'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems.rb:220:in `rescue in try_activate'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems.rb:213:in `try_activate'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:126:in `rescue in require'
	from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:40:in `require'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider.rb:77:in `requires'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider/openshift.rb:6:in `<class:Openshift>'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider/openshift.rb:3:in `<class:Provider>'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider/openshift.rb:2:in `<module:DPL>'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider/openshift.rb:1:in `<top (required)>'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider.rb:59:in `const_get'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider.rb:59:in `block in new'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/cli.rb:41:in `fold'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/provider.rb:56:in `new'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/cli.rb:31:in `run'
	from /usr/local/bundle/gems/dpl-1.8.31/lib/dpl/cli.rb:7:in `run'
	from /usr/local/bundle/gems/dpl-1.8.31/bin/dpl:5:in `<top (required)>'
	from /usr/local/bundle/bin/dpl:22:in `load'
	from /usr/local/bundle/bin/dpl:22:in `<main>'

I tried to use different version of ruby: 1.9, 2.0, 2.4, etc, but without success.