~/reply$ lein do deps, compile
Compiling 2 source files to /home/ubuntu/reply/target/classes
error: Source option 1.5 is no longer supported. Use 1.6 or later.
error: Target option 1.5 is no longer supported. Use 1.6 or later.
Compilation of Java sources(lein javac) failed.
~/reply$ java -version
openjdk version "9-internal"
OpenJDK Runtime Environment (build 9-internal+0-2016-04-14-195246.buildd.src)
OpenJDK 64-Bit Server VM (build 9-internal+0-2016-04-14-195246.buildd.src, mixed mode)
I think this is due to the jvm-opts in project.clj. Related issue : https://github.com/jline/jline2/issues/220