Undefined variable exception while evaluating Do-Until loop

[gray...@gmail.com]

My Do-Until loop errors out if the until condition checks against a value that happens to contain a string like "{{ var }}". I stepped through the Ansible code and it attempts to evaluate "var" then throws an undefined variable exception. I have no control over what echo_result.stdout contains. How can I ask jinja2 to skip nested variable substitution and leave "{{ var }}" as is while evaluating the until condition?

I have simplified the scenario down to the following playbook below. Thanks in advance.

#Ansible version:
#  Branch: devel
#  Commit: 2015-10-28 bdf5f70 James Cammarata      Merge pull request #12950 from chrismeyersfsu/fix-ansible_test_service_checksum

- hosts: localhost
  gather_facts: no
  sudo: yes
  tasks:
    - name: Set facts
      set_fact:
        lb: '{'
        v: 'x'
        rbs: '}}'

    # works
    - name: Echo a variable
      command: echo "abc {{ v }}"
      register: echo_result
      until: "echo_result.stdout.find('abc') != -1"
    - debug: var=echo_result

    # breaks
    - name: Echo a nested jinja2 variable
      command: echo "abc {{ lb }}{{ lb }} {{ v }} {{ rbs }}"
      register: echo_result
      until: "echo_result.stdout.find('abc') != -1"
    - debug: var=echo_result