Catch interrupted exception in shell
Catch interrupted exception in shell

I noticed in CI that sometimes the client tests exit with an interrupted
exception printed. I tracked it down the exception to the call to
getExec, which delegateds to CommandExchange.blockUntilNextExec.

sbt/sbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,mdedetrich/sbt,mdedetrich/sbt,mdedetrich/sbt,xuwei-k/xsbt,xuwei-k/xsbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,xuwei-k/xsbt,xuwei-k/xsbt,xuwei-k/xsbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,mdedetrich/sbt