$ copy-file changes/A.scala src/main/scala/A.scala
> compile

$ copy-file changes/A2.scala src/main/scala/A.scala
> compile

$ copy-file changes/B.scala src/main/scala/B.scala
-> compile

$ copy-file changes/A.scala src/main/scala/A.scala
> compile

$ delete src/main/scala/B.scala
$ copy-file changes/A2.scala src/main/scala/A.scala
> compile

$ copy-file changes/A.scala src/main/scala/A.scala
$ copy-file changes/B.scala src/main/scala/B.scala
> compile