Upstart script exported by Foreman not working properly, respawning too fast

The only error I could find out was looking at dmesg

[ 603.598951] init: thx4-web-1 main process ended, respawning
[ 603.607935] init: thx4-web-1 main process (3901) terminated with status 127
[ 603.607988] init: thx4-web-1 main process ended, respawning
[ 603.616866] init: thx4-web-1 main process (3903) terminated with status 127
[ 603.616917] init: thx4-web-1 respawning too fast, stopped

OS: Debian 7 , chruby (2.1.2), upstart (1.6.1-1) and foreman (0.74.0)

Only one process, to simplify the process in Procfile.staging :

web: RAILS_ENV=staging bundle exec puma -e staging -C config/puma.rb

Generated files:

# /etc/init/thx4.conf
start on runlevel [2345]
stop on runlevel [!2345
]
# /etc/init/thx4-web.conf
start on starting thx4
stop on stopping thx4
# /etc/init/thx4-web-1.conf
start on starting thx4-web
stop on stopping thx4-web
respawn
env PORT=5000
setuid deployer
chdir /home/deployer/apps/thx4/releases/20140707183433
exec RAILS_ENV=staging bundle exec puma -e staging -C config/puma.rb

When i run $ foreman start -f Procfile.staging inside app folder, all it works fine.

Same question at StackOverflow: upstart-script-exported-by-foreman-not-working