Behavior of Clean when /graphBuild and /p:BuildProjectReferences=false is set for traversal projects

[pubudu91]

I have the following scenario:

• I have a group of related projects that make up a component and I want to define a traversal project for it.
• When building the traversal project, I don't want to build any projects that are not listed in the traversal project (project refs to projects outside of the traversal project/component). But I also want to build the projects listed in the traversal project in topological order.
• To achieve this, I used the /graphBuild (to make it build in the correct order) and /p:BuildProjectReferences=false (to ensure it doesn't build any projects not listed in the traversal project).
• This works perfectly when running Build.
• But when trying to run Clean, it doesn't show the above behavior. It cleans up all the projects in the graph. I don't want that to happen since I'm fetching the dependencies using a separate tool (so the build assumes all the artifacts of the referenced projects are available). But since Clean now cleans up those as well, the build fails.
• So instead of running a single MSBuild command with /t:Clean;Build, I have to run two separate commands, one for Clean and one for Build.

What I wanted to know is, is this behavior the expected behavior or a bug in how Clean works? If it's the expected behavior, why is that? Shouldn't it work the same for any target?