Redmine

When i enable rufus-scheduler it doesn't seem to do anything, it also doesn't output any noticeable errors. Fetching mail works fine through regular cron. How can i debug this?

redmine: 3.0.3
nginx: 1.8.0
fusion passenger: 5.0.10
rufus-scheduler: 3.1.3

/config/initializers/fetchmail.rb

require 'rubygems'
require 'rake'
require 'rufus-scheduler'

load File.join(Rails.root, 'Rakefile')

ENV['host']='imap.gmail.com'
ENV['port']='993'
ENV['ssl']='SSL'
ENV['username']='<username>'
ENV['password']='<password>'
ENV['move_on_success']='Success'
ENV['move_on_failure']='Failed'

scheduler = Rufus::Scheduler.new

scheduler.interval '5m' do
  task = Rake.application['redmine:email:receive_imap']
  task.reenable
  task.invoke 
end

Restart:

[ 2015-07-03 14:00:40.2559 3801/7fb96742b740 age/Wat/Main.cpp:1293 ]: Starting PassengerAgent watchdog...
[ 2015-07-03 14:00:40.2614 3804/7f18d68c1740 age/Hel/Main.cpp:957 ]: Starting PassengerAgent server...
[ 2015-07-03 14:00:40.2616 3804/7f18d68c1740 age/Hel/Main.cpp:234 ]: PassengerAgent server running in multi-application mode.
[ 2015-07-03 14:00:40.2630 3804/7f18d68c1740 age/Hel/Main.cpp:707 ]: PassengerAgent server online, PID 3804
[ 2015-07-03 14:00:40.2686 3809/7fa218249740 age/Log/Main.cpp:430 ]: Starting PassengerAgent logger...
[ 2015-07-03 14:00:40.2692 3809/7fa218249740 age/Log/Main.cpp:311 ]: PassengerAgent logger online, PID 3809
App 3848 stdout: 
App 3848 stderr: sh: 1: 
App 3848 stderr: env: not found
App 3848 stderr: 
App 3865 stdout:

I'm not sure what the env: not found message above means, but it also appears without rufus-scheduler enabled so i suspect it is unrelated.

Thanks for any insight!