> compile

# restore core's early jar from the disk cache, then leave it as a read-only regular file
$ delete target/out
> compile
> core/makeEarlyJarReadOnly

# an incremental round in core must still be able to update the early jar
$ copy-file changes/Added.scala core/Added.scala
$ copy-file changes/UseAdded.scala app/UseAdded.scala
> compile
> app/checkEarlyJar
