Ctrl-B does not jump to library source

I have a library, let's call it foo.jar.  I added it as a dependency to one of my modules (call it module M) and attached the source to the library.  Now when I Ctrl-B on codes that invoke a method from foo.jar, Intellij takes me to the source code definition of the method.   Everything is good.

Later on, I created another module foo within the same project with the source of foo.jar.   I did this because I wanted to experiment with some local changes to the library, but I still keep module M dependent on the original foo.jar, not the locally built one.  Now suddenly when I Ctrl-B on the same method invokation, I am taken to the decompiled .class file rather than the source of foo.jar, even though I still have the source attatched.

What is the rational for this behavior and is there a way to work around this?  I am running community edition 9.0.3, build #IC95,429.  My JDK is 1.6.0_22 and I am running hotspt JVM.  Thanks.