$ copy-file changes/A.scala src/main/scala/A.scala
[success]

> compile
[success]

$ copy-file changes/A2.scala src/main/scala/A.scala
[success]

> compile
[success]

$ copy-file changes/B.scala src/main/scala/B.scala
[success]

> compile
[failure]

$ copy-file changes/A.scala src/main/scala/A.scala
[success]

> compile
[success]

$ delete src/main/scala/B.scala
[success]

$ copy-file changes/A2.scala src/main/scala/A.scala
[success]

> compile
[success]

$ copy-file changes/A.scala src/main/scala/A.scala
[success]

$ copy-file changes/B.scala src/main/scala/B.scala
[success]

> compile
[success]
