In order to support legacy plugins, the following two method signatures
are allowed for `CallbackBase.v2_playbook_on_start`:
def v2_playbook_on_start(self):
def v2_playbook_on_start(self, playbook):
Previously, the logic to handle this divergence checked to see if the
callback plugin being called supported an argument named `playbook`
in its `v2_playbook_on_start` method. This was fragile in a few ways:
- if a plugin author did not use the literal `playbook` to name their
method argument, their plugin would not be called correctly
- if a plugin author wrapped their `v2_playbook_on_start` method and
by doing so changed the argspec to no longer expose an argument
with that literal name, their plugin would not be called correctly
In order to continue to support both types of callback for backwards
compatibility while making the call more robust for plugin authors,
the logic can be reversed in order to have a positive check for the old
method signature instead of a positive check for the new one.
Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>
