Cannot get password from a vault file

Dear all,

I am really stucked with this problem.
I have a vault file which is referenced within ansible.cfg and its password is stored in a file referenced on the command line through --vault-password-file.
This seems to be ok.

My vault contains (silly example for trials):

jenkins: totototo

I thought that I had understood that jenkins is considered as a var ( by the way, the file is included through include_vars), and therefore must be used as {{ jenkins }}.
And as it is about password used to create a user, the task could be something like :

`

-name: Create Jenkins User
user:
name: jenkins
groups: jenkins
state: present
password: “{{ jenkins | password_hash(‘sha512’) }}”
comment: “Jenkins Instance user”
createhome: yes
home: /home/jenkins
shell: /usr/bin/bash
become: yes
become_user: root

`

The playbook runs OK.
But when going into the machine (a VM created with vagrant) through ssh as vagrant user, I cannot run su jenkins. The password totototo is refused.
Note that if I replace the password line with :
*password: "{{ 'totototo' | password_hash('sha512') }}"*
I can run a su jenkins with password totototo.

So … what ?

Thanks for your help.
J-L