Eugene Yokota 06ffb4f440 warn about multiple instance once ... Fixes #3823 When you launch a second instance of sbt on a build, prior to this change it was displaying `java.io.IOException: sbt server is already running` on every command. This make it a bit less aggressive, and just display a warning once. ``` [warn] Is another instance of sbt is running on this build? [warn] Running multiple instances is unsupported ```		2017-12-20 10:09:03 -05:00
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src	warn about multiple instance once	2017-12-20 10:09:03 -05:00
NOTICE	Add, configure & enforce file headers	2017-10-05 09:03:40 +01:00