emerge gitlab-shell-10.0.0 fails (Bundler says it needs sudo access)

The new version of gitlab-shell fails to emerge on my system. I'm trying to update from version 9.3.0. I've attached emerge --info and build.log, and copied the relevant portion below:

>>> Compiling source in /var/tmp/portage/dev-vcs/gitlab-shell-10.0.0/work ...
 * Running compile phase for ruby25 ...
 * Running "bundle install" ...
 * ACCESS DENIED:  open_wr:      /usr/lib64/ruby/gems/2.5.0/bundler.lock
Fetching gem metadata from https://rubygems.org/..........
Using rake 12.3.3
Following files may not be writable, so sudo is needed:
  /usr/bin                                                                      
  /usr/lib64/ruby/gems/2.5.0                                                    
  /usr/lib64/ruby/gems/2.5.0/gems                                               
  /usr/lib64/ruby/gems/2.5.0/specifications                                     
Fetching abstract_type 0.0.7
ERROR: ld.so: object 'libsandbox.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.



Your user account isn't allowed to install to the system RubyGems.
  You can cancel this installation and run:

      bundle install --path vendor/bundle

  to install the gems into ./vendor/bundle/, or you can enter your password
  and install the bundled gems to RubyGems using sudo.

  Password: 
sudo: timed out reading password
Bundler::SudoNotPermittedError: Bundler requires sudo access to install at the
moment. Try installing again, granting Bundler sudo access when prompted, or    
installing into a different path.                                               
An error occurred while installing abstract_type (0.0.7), and                   
Bundler cannot continue.                                                        
Make sure that `gem install abstract_type -v '0.0.7' --source                   
'https://rubygems.org/'` succeeds before bundling.                              

In Gemfile:
  rspec-parameterized was resolved to 0.4.0, which depends on
    proc_to_ast was resolved to 0.1.0, which depends on
      unparser was resolved to 0.2.8, which depends on
        abstract_type

I tried entering the password and it makes no difference.