Capistrano error : could not connect to ssh-agent

Hello!
I’m using Bedrock with Capistrano deploys.
When I use command bundle exec cap staging deploy:check I get an authentication error :

...
D, [2015-05-09T15:39:53.878464 #15636] DEBUG -- net.ssh.authentication.session[1e34a58]: trying publickey
D, [2015-05-09T15:39:53.878464 #15636] DEBUG -- net.ssh.authentication.agent[1e30d2c]: connecting to ssh-agent
E, [2015-05-09T15:39:53.879447 #15636] ERROR -- net.ssh.authentication.agent[1e30d2c]: could not connect to ssh-agent
E, [2015-05-09T15:39:53.879447 #15636] ERROR -- net.ssh.authentication.session[1e34a58]: all authorization methods failed (tried publickey)
cap aborted!
SSHKit::Runner::ExecuteError: Exception while executing as deploy@SERVER_IP: Authentication failed for user deploy@SERVER_IP
Tasks: TOP => git:check => git:wrapper

Capistrano could not connect to ssh-agent on my server.

But I can log in on my server via SSH like this ssh deploy@SERVER_IP without password. I dit all the instructions in Capistrano Authentication & Authorisation Docs page, so I can use command like me@localhost $ ssh deploy@one-of-my-servers.com ‘hostname; uptime’.

If I enter command ssh -A deploy@SERVER_IP 'env | grep SSH_AUTH_SOCK' I get result

SSH_AUTH_SOCK=/tmp/ssh-UweQkw7578/agent.7578

Here is my deploy.rb file :

set :application, 'dyxovka-special'
set :repo_url, 'git@github.com:tanzoor/dyxovka-wp-theme.git'
set :branch, :master
set :tmp_dir, '~/tmp'
set :log_level, :info
set :linked_files, fetch(:linked_files, []).push('.env')
set :linked_dirs, fetch(:linked_dirs, []).push('web/app/uploads')

Here is my staging.rb file :

set :stage, :staging
set :deploy_to, -> { "/var/www/vhosts/project/dev" }
server 'SERVER_IP', user: 'deploy', roles: %w{web app}
set :ssh_options, {
  user: 'deploy',
  keys: %w('/c/Users/alexander/.ssh/id_rsa'),
  forward_agent: true,
  auth_methods: %w(publickey),
  verbose: :debug
}
fetch(:default_env).merge!(wp_env: :staging)

Apache’s agent forwarding agent instruction is enabled in sshd_config file : AllowAgentForwarding yes

What should do with my config files to make my deploy work?

Windows 8.1
Ruby 2.2.0
Capistrano 3.2.1
Git Bash

Try following this article as well as it has some tips about SSH forwarding set up/debugging.