Hi,

while upgrading my Pulp Proxy from Katello 3.4 to 3.5, I encountered the following error:
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/catalog.rb:608:in `fail_on_duplicate_type_and_title'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/catalog.rb:133:in `add_one_resource'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/catalog.rb:119:in `block in add_resource'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/catalog.rb:118:in `each'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/catalog.rb:118:in `add_resource'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:107:in `add_resource'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/runtime3_resource_support.rb:58:in `block in create_resources'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/runtime3_resource_support.rb:37:in `map'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/runtime3_resource_support.rb:37:in `create_resources'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/runtime3_support.rb:350:in `create_resources'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:842:in `block in eval_ResourceExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:839:in `map'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:839:in `eval_ResourceExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/visitor.rb:69:in `visit_this_1'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:82:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:1005:in `block in eval_IfExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/scope.rb:980:in `with_guarded_scope'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:1003:in `eval_IfExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/visitor.rb:69:in `visit_this_1'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:82:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:638:in `block in eval_BlockExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:638:in `each'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:638:in `reduce'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:638:in `eval_BlockExpression'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/visitor.rb:69:in `visit_this_1'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/evaluator/evaluator_impl.rb:82:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/pops/parser/evaluating_parser.rb:63:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:32:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:72:in `block (2 levels) in evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:71:in `catch'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:71:in `block in evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:70:in `catch'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast/pops_bridge.rb:70:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/ast.rb:31:in `safeevaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/resource/type.rb:184:in `evaluate_code'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/resource.rb:81:in `block in evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler/around_profiler.rb:58:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler.rb:51:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/resource.rb:73:in `evaluate'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:587:in `block (3 levels) in evaluate_definitions'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:585:in `each'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:585:in `block (2 levels) in evaluate_definitions'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler/around_profiler.rb:58:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler.rb:51:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:584:in `block in evaluate_definitions'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/errors.rb:64:in `exceptwrap'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:583:in `evaluate_definitions'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:616:in `block (2 levels) in evaluate_generators'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler/around_profiler.rb:58:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler.rb:51:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:613:in `block in evaluate_generators'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:610:in `loop'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:610:in `evaluate_generators'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:191:in `block (2 levels) in compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler/around_profiler.rb:58:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler.rb:51:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:191:in `block in compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/context.rb:65:in `override'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet.rb:306:in `override'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:166:in `compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/parser/compiler.rb:33:in `compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/indirector/catalog/compiler.rb:269:in `block (2 levels) in compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler/around_profiler.rb:58:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/profiler.rb:51:in `profile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/indirector/catalog/compiler.rb:267:in `block in compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util.rb:224:in `block in benchmark'
/opt/puppetlabs/puppet/lib/ruby/2.1.0/benchmark.rb:294:in `realtime'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util.rb:223:in `benchmark'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/indirector/catalog/compiler.rb:265:in `compile'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/indirector/catalog/compiler.rb:55:in `find'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/indirector/indirection.rb:194:in `find'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/application/apply.rb:256:in `block in main'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/context.rb:65:in `override'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet.rb:306:in `override'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/application/apply.rb:225:in `main'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/application/apply.rb:170:in `run_command'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/application.rb:358:in `block in run'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util.rb:662:in `exit_on_fail'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/application.rb:358:in `run'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/command_line.rb:132:in `run'
/opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/command_line.rb:72:in `execute'
/opt/puppetlabs/bin/puppet:5:in `<main>'

And from the log:
Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Error while evaluating a Resource Statement, Duplicate declaration: File[/etc/foreman-proxy/ssl_key.pem] is already declared in file /usr/share/foreman-installer/modules/foreman_proxy/manifests/config.pp:154; cannot redeclare at /usr/share/katello-installer-base/modules/certs/manifests/keypair.pp:23 at /usr/share/katello-installer-base/modules/certs/manifests/keypair.pp:23:5 at /usr/share/katello-installer-base/modules/certs/manifests/foreman_proxy.pp:84

I modified /usr/share/katello-installer-base/modules/certs/manifests/keypair.pp and removed the following block:
if $manage_key {
file { $key_file:
ensure => file,
owner => $key_owner,
group => $key_group,
mode => $key_mode,
require => Privkey[$key_file],
}
}

With that modification, the installer finished without errors, but I am not sure if this can break some thins in other scenarios.