This bug appears in BETA4 and RC1, it was not present in BETA3 - so it is likely to do with the new configuration changes.
I'll try and depict things clearly for debuggers and then anyone who happens to be working around the bug today like me (ie If you want to continue testing!)
The specific behavior i am experiencing this issue with is in 'sfPropelActAsNestedSetBehaviorPlugin', but it's applicable to all.
The Bug) If i launch the "propel:build-forms" task, it throws:
Propel behavior "actasnestedset" is not registered
Although the behavior is clearly defined correctly in the schema.yml it is not 'registered' in said task.
The issue seems to be related in loading the configuration.
Workaround/Hack) It can be forced into working by doing the following hack, edit 'sfPropelPlugin/lib/task/sfPropelBuildFormsTask.class.php' and place the below on line 64
ProjectConfiguration::getApplicationConfiguration('frontend', 'cli', true);
The above hack gets things operational again within that task, however it causes the next issue which ill document for anyone wanting to use it to continue testing.
The Hack Fallout) Now if you launch "propel:build-all-load <app>" it tries to mixin the behaviour twice resulting in the following error:
The class "Base<model>" has already a mixin for method "getLeftValue".
This is caused by the above hack, so if you happen to be using the hack you can work around this by doing the propel:build-all and then subsequent propel:data-load tasks.
Such as:
php symfony propel:build-all
php symfony propel:data-load <app>
