koji_promote ends with INFO - Not promoting failed build to koji

[rcerven]

this relates to the change, where dockerfile_content was removed

in plugin.py PluginsRunner

self.on_plugin_failed() is called and sets plugin_failed to True,
even when plugin
plugin 'dockerfile_content' requested but not available
even when in prod_inner.json the plugin has set required to False

so based on that even when inside container build is success, but this not required plugin sets plugin_failed
koji_promote won't promote anything