Capistrano 3 doesn't work with bundler warning (bundler-unload)

Question

I have a bundler warning during cap deploy in the begin of bundle:install :

WARN: Unresolved specs during Gem::Specification.reset:
DEBUG [9c13fdda]    
DEBUG [9c13fdda]          bundler-unload (>= 1.0.1)
DEBUG [9c13fdda]    
DEBUG [9c13fdda]    WARN: Clearing out unresolved specs.
DEBUG [9c13fdda]    
DEBUG [9c13fdda]    Please report a bug if this causes problems.
DEBUG [9c13fdda]    
DEBUG [9c13fdda]    Fetching gem metadata from https://rubygems.org/
DEBUG [9c13fdda]    .

But gems are install successfully.

And then capistrano fails when trying to run assets:precompile because it can't find all the previously installed gems:

Command: cd /home/web/www/project/releases/20131101111717 && ( RAILS_ENV=staging /usr/local/rvm/bin/project_rake assets:precompile )
DEBUG [e3973943]    /usr/local/rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/spec_set.rb:92:in `block in materialize'
DEBUG [e3973943]    : 
DEBUG [e3973943]    Could not find multi_json-1.7.9 in any of the sources
DEBUG [e3973943]     (
DEBUG [e3973943]    Bundler::GemNotFound
DEBUG [e3973943]    )

Answer 1

This removes the warning and fixes the Bundler::GemNotFound error

on the server:

gem uninstall bundler-unload
gem install rubygems-bundler