allow ansible_ssh_password as it is documented as valid in current ansible documentation

Co-authored-by: Alex Willmer <alex@moreati.org.uk>

ansible_mitogen/transport_config.py

@@ -678,6 +678,7 @@ class MitogenViaSpec(Spec):
 
     def password(self):
         return optional_secret(
+            self._host_vars.get('ansible_ssh_password') or
             self._host_vars.get('ansible_ssh_pass') or
             self._host_vars.get('ansible_password')
         )

docs/ansible_detailed.rst

@@ -306,7 +306,8 @@ container.
     * Intermediary machines cannot use login and become passwords that were
       supplied to Ansible interactively. If an intermediary requires a
       password, it must be supplied via ``ansible_ssh_pass``,
-      ``ansible_password``, or ``ansible_become_pass`` inventory variables.
+      ``ansible_ssh_password``, ``ansible_password``, or
+      ``ansible_become_pass`` inventory variables.
 
     * Automatic tunnelling of SSH-dependent actions, such as the
       ``synchronize`` module, is not yet supported. This will be addressed in a
@@ -1011,7 +1012,8 @@ Like the :ans:conn:`ssh` except connection delegation is supported.
 * ``ansible_port``, ``ssh_port``
 * ``ansible_ssh_executable``, ``ssh_executable``
 * ``ansible_ssh_private_key_file``
-* ``ansible_ssh_pass``, ``ansible_password`` (default: assume passwordless)
+* ``ansible_ssh_pass``, ``ansible_ssh_password``, ``ansible_password``
+  (default: assume passwordless)
 * ``ssh_args``, ``ssh_common_args``, ``ssh_extra_args``
 * ``mitogen_mask_remote_name``: if :data:`True`, mask the identity of the
   Ansible controller process on remote machines. To simplify diagnostics,