ansible_ssh_args not cleared through Inventory file entry

I have installed the latest version of ansible by cloning the source:

sandman(maf):~:667:$ ansible --version
ansible 2.0.0 (devel 05f6e76407) last updated 2015/09/19 12:16:52 (GMT -400)
lib/ansible/modules/core: (detached HEAD 59afecace4) last updated 2015/09/19 12:16:58 (GMT -400)
lib/ansible/modules/extras: (detached HEAD dee690d7f4) last updated 2015/09/19 12:17:02 (GMT -400)
config file =
configured module search path = None

I am running Python 2.6.6 with Debian squeeze.

Running ansible the first time gives me:

sandman(maf):~:661:$ ansible all -m ping
mmm | FAILED! => {
“failed”: true,
“msg”: “ERROR! using -c ssh on certain older ssh versions may not support ControlPersist, set ANSIBLE_SSH_ARGS="" (or ssh_args in [ssh_connection] section of the config file) before running again”
}

I update my Inventory file as below:

mmm ansible_connection=ssh ansible_ssh_host=maestro.knocout.com ansible_ssh_port=22 ansible_ssh_user=maf ansible_ssh_args=""

I get the same error message running ansible again:

sandman(maf):~:655:$ ansible all -vvv -m ping
No config file found; using defaults
<maestro.knocout.com> ESTABLISH SSH CONNECTION FOR USER: maf
<maestro.knocout.com> EXEC ssh -C -tt -q -o ControlMaster=auto -o ControlPersist=60s -o ControlPath=“/home/maf/.ansible/cp/ansible-ssh-%h-%p-%r” -o Port=22 -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 maestro.knocout.com (umask 22 && mkdir -p “$HOME/.ansible/tmp/ansible-tmp-1442679825.67-6473289374010” && echo “$HOME/.ansible/tmp/ansible-tmp-1442679825.67-6473289374010”)
mmm | FAILED! => {
“failed”: true,
“msg”: “ERROR! using -c ssh on certain older ssh versions may not support ControlPersist, set ANSIBLE_SSH_ARGS="" (or ssh_args in [ssh_connection] section of the config file) before running again”
}

The Inventory file is certainly being accessed as it is picking up the host alias and other information but it is not clearing the ansible_ssh_args.

I get the same error when the Inventory file is as below:

mmm ansible_connection=ssh ansible_ssh_host=maestro.knocout.com ansible_ssh_port=22 ansible_ssh_user=maf ansible_ssh_args=“”

When I specify some other value for ansible_ssh_args in the Inventory file, I get the following error:

mmm ansible_connection=ssh ansible_ssh_host=maestro.knocout.com ansible_ssh_port=22 ansible_ssh_user=maf ansible_ssh_args=“ControlPersist=60s”

sandman(maf):~:657:$ ansible all -vvv -m ping
No config file found; using defaults
<maestro.knocout.com> ESTABLISH SSH CONNECTION FOR USER: maf
<maestro.knocout.com> EXEC ssh -C -tt -q ControlPersist=60s -o Port=22 -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 maestro.knocout.com (umask 22 && mkdir -p “$HOME/.ansible/tmp/ansible-tmp-1442680096.76-134194356604434” && echo “$HOME/.ansible/tmp/ansible-tmp-1442680096.76-134194356604434”)
An exception occurred during task execution. The full traceback is:
Traceback (most recent call last):
File “/home/maf/opt/ansible/lib/ansible/executor/process/worker.py”, line 122, in run
executor_result = TaskExecutor(host, task, job_vars, new_play_context, self._new_stdin, self._loader, shared_loader_obj).run()
File “/home/maf/opt/ansible/lib/ansible/executor/task_executor.py”, line 120, in run
res = self._execute()
File “/home/maf/opt/ansible/lib/ansible/executor/task_executor.py”, line 341, in _execute
result = self._handler.run(task_vars=variables)
File “/home/maf/opt/ansible/lib/ansible/plugins/action/normal.py”, line 26, in run
results = self._execute_module(tmp=tmp, task_vars=task_vars)
File “/home/maf/opt/ansible/lib/ansible/plugins/action/init.py”, line 357, in _execute_module
tmp = self._make_tmp_path()
File “/home/maf/opt/ansible/lib/ansible/plugins/action/init.py”, line 173, in _make_tmp_path
result = self._low_level_execute_command(cmd, None, sudoable=False)
File “/home/maf/opt/ansible/lib/ansible/plugins/action/init.py”, line 463, in _low_level_execute_command
rc, stdin, stdout, stderr = self._connection.exec_command(cmd, tmp, in_data=in_data, sudoable=sudoable)
File “/home/maf/opt/ansible/lib/ansible/plugins/connection/ssh.py”, line 318, in exec_command
raise e
TypeError: execv() arg 2 must contain only strings

mmm | FAILED! => {
“failed”: true,
“stdout”: “”
}

Any suggestions on what I might do to fix the problem?

Thanks