Pipeline buildCluster annotation is not deleted

[yuichi10]

What happened:

If the user sets the `screwdriver.cd/buildCluster' annotation to pipeline level, even if the user deletes the setting, the setting is not deleted.

What you expected to happen:

It will run on the default build cluster if you remove the pipeline level annotation.

How to reproduce it:

1. set the pipeline level screwdriver.cd/buildCluster annotation.
2. remove the annotation.
3. run build and the build will run on the cluster you set in the first step.

[jithine]

we save buildCluster into the Pipeline table at creation time of if the annotation changes. What should be the behavior once annotation is removed ? Let SD reset it to default ?

[yuichi10]

Resetting to default seems to be a good idea.