Ansible command-task runs into “Exec format error”

I wrote this ansible task to run a process on a remote vagrant box. (Well, actually the ansible file itself is much longer, but this is a reproducer that only runs the start script.)

---
- hosts: myappname_server
  vars_files:
    - install_myappname_vars.yaml
  gather_facts: false
  sudo: true
  sudo_user: "{{ project_name }}"

  tasks:
  - name: Restart application
    command: "{{ project_target_dir_env }}/run"
    args:
      chdir: "{{ project_target_dir_env }}"

It works with these vars in the included vars file:

---
project_name: myappname
project_source_dir_files: files/myappname
project_source_dir_env: "{{ project_source_dir_files }}/environment_files"
project_target_root: /home/myappname
project_target_dir_env: "{{ project_target_root }}/bin"

The idea is to use user "myappname" on the remote box (aliased correctly by "myappname_server", other plays I run against is work just fine) to run "/home/myappname/bin/run" after changing the directory to "/home/myappname/bin". If I do that manually, everything works fine, i.e. the dirs exist, the files are readable, the script works etc., all great. But if I execute the script, something seems to be wrong with the generation of the ansible execution code. Is it me and my config hope so)? Is it ansible?

I ran it with -vvvv to get a lot of information:

monsterkill@monsterkill-ub-dt:~/playbooks$ ansible-playbook install_myappname_restart.yaml -vvvv

PLAY [myappname_server] ********************************************************** 

TASK: [Restart application] *************************************************** 
<vagrant1> ESTABLISH CONNECTION FOR USER: vagrant
<vagrant1> REMOTE_MODULE command chdir=/home/myappname/bin /home/myappname/bin/run
<vagrant1> EXEC ['ssh', '-C', '-tt', '-vvv', '-o', 'ControlMaster=auto', '-o', 'ControlPersist=60s', '-o', 'ControlPath=/home/monsterkill/.ansible/cp/ansible-ssh-%h-%p-%r', '-o', 'Port=22', '-o', 'IdentityFile=/home/monsterkill/insecure_private_key', '-o', 'KbdInteractiveAuthentication=no', '-o', 'PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey', '-o', 'PasswordAuthentication=no', '-o', 'User=vagrant', '-o', 'ConnectTimeout=10', 'vagrant1', "/bin/sh -c 'mkdir -p /tmp/ansible-tmp-1422343063.07-259463565013754 && chmod a+rx /tmp/ansible-tmp-1422343063.07-259463565013754 && echo /tmp/ansible-tmp-1422343063.07-259463565013754'"]
<vagrant1> PUT /tmp/tmpBduhE7 TO /tmp/ansible-tmp-1422343063.07-259463565013754/command
<vagrant1> EXEC ['ssh', '-C', '-tt', '-vvv', '-o', 'ControlMaster=auto', '-o', 'ControlPersist=60s', '-o', 'ControlPath=/home/monsterkill/.ansible/cp/ansible-ssh-%h-%p-%r', '-o', 'Port=22', '-o', 'IdentityFile=/home/monsterkill/insecure_private_key', '-o', 'KbdInteractiveAuthentication=no', '-o', 'PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey', '-o', 'PasswordAuthentication=no', '-o', 'User=vagrant', '-o', 'ConnectTimeout=10', 'vagrant1', "/bin/sh -c 'chmod a+r /tmp/ansible-tmp-1422343063.07-259463565013754/command'"]
<vagrant1> EXEC ['ssh', '-C', '-tt', '-vvv', '-o', 'ControlMaster=auto', '-o', 'ControlPersist=60s', '-o', 'ControlPath=/home/monsterkill/.ansible/cp/ansible-ssh-%h-%p-%r', '-o', 'Port=22', '-o', 'IdentityFile=/home/monsterkill/insecure_private_key', '-o', 'KbdInteractiveAuthentication=no', '-o', 'PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey', '-o', 'PasswordAuthentication=no', '-o', 'User=vagrant', '-o', 'ConnectTimeout=10', 'vagrant1', u'/bin/sh -c \'sudo -k && sudo -H -S -p "[sudo via ansible, key=ucmsbsauynfzeeyxwdmgfduwovdneeqg] password: " -u myappname /bin/sh -c \'"\'"\'echo SUDO-SUCCESS-ucmsbsauynfzeeyxwdmgfduwovdneeqg; /usr/bin/python /tmp/ansible-tmp-1422343063.07-259463565013754/command\'"\'"\'\'']
<vagrant1> EXEC ['ssh', '-C', '-tt', '-vvv', '-o', 'ControlMaster=auto', '-o', 'ControlPersist=60s', '-o', 'ControlPath=/home/monsterkill/.ansible/cp/ansible-ssh-%h-%p-%r', '-o', 'Port=22', '-o', 'IdentityFile=/home/monsterkill/insecure_private_key', '-o', 'KbdInteractiveAuthentication=no', '-o', 'PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey', '-o', 'PasswordAuthentication=no', '-o', 'User=vagrant', '-o', 'ConnectTimeout=10', 'vagrant1', "/bin/sh -c 'rm -rf /tmp/ansible-tmp-1422343063.07-259463565013754/ >/dev/null 2>&1'"]
failed: [vagrant1] => {"cmd": ["/home/myappname/bin/run"], "failed": true, "rc": 8}
msg: [Errno 8] Exec format error

FATAL: all hosts have already failed -- aborting

PLAY RECAP ******************************************************************** 
           to retry, use: --limit @/home/monsterkill/install_myappname_restart.yaml.retry

vagrant1                   : ok=0    changed=0    unreachable=0    failed=1   

I tried things like:

• playing around with slashes after the directory
• using with relative and absolute paths on the remote machine
• work with and without sudo and sudo_user in my tasks

I know that all other ansible modules I use with the same bunch of vars from some neighbouring playbooks work just fine. Also built-in stuff, like group, user, file, apt, unarchive, copy. Note that a number of these also require the group/user stuff to be correct, so I know that's all fine as well.

/edit: I also know that the path to the run script is correct, because if I rename the run script and run the playbook, I get another error ("msg: [Errno 2] No such file or directory", as expected). So it's actually trying to run the existing run script, but failing.

But nothing seems to work. What is going on, what is wrong with that last piece of generated EXEC stuff? Thanks for your time.