apache/incubator-spark — pull request #71 by aarondav (2013-10-18 01:56:58+00:00)
Title: Spark shell exits if it cannot create SparkContext

Mainly, this occurs if you provide a messed up MASTER url (one that doesn't match one
of our regexes). Previously, we would default to Mesos, fail, and then start the shell
anyway, except that any Spark command would fail. Simply exiting seems clearer.