https://github.com/harrah/xsbtの指示に従って sbt 0.12.0-RC1 をビルドしようとしていますが、以前のバージョンの sbt をダウンロードできません。
Getting org.scala-sbt sbt_2.9.1 0.12.0-M2 ...
:: problems summary ::
:::: WARNINGS
module not found: org.scala-sbt#sbt_2.9.1;0.12.0-M2
==== local: tried
/home/k/.ivy2/local/org.scala-sbt/sbt_2.9.1/0.12.0-M2/ivys/ivy.xml
==== typesafe-ivy-releases: tried
http://repo.typesafe.com/typesafe/ivy-releases/org.scala-sbt/sbt_2.9.1/0.12.0-M2/ivys/ivy.xml
==== Maven Central: tried
http://repo1.maven.org/maven2/org/scala-sbt/sbt_2.9.1/0.12.0-M2/sbt_2.9.1-0.12.0-M2.pom
==== sonatype-snapshots: tried
https://oss.sonatype.org/content/repositories/snapshots/org/scala-sbt/sbt_2.9.1/0.12.0-M2/sbt_2.9.1-0.12.0-M2.pom
::::::::::::::::::::::::::::::::::::::::::::::
:: UNRESOLVED DEPENDENCIES ::
::::::::::::::::::::::::::::::::::::::::::::::
:: org.scala-sbt#sbt_2.9.1;0.12.0-M2: not found
::::::::::::::::::::::::::::::::::::::::::::::
:: USE VERBOSE OR DEBUG MESSAGE LEVEL FOR MORE DETAILS
unresolved dependency: org.scala-sbt#sbt_2.9.1;0.12.0-M2: not found
Error during sbt execution: Error retrieving required libraries
(see /home/k/.sbt/boot/update.log for complete log)
Error: Could not retrieve sbt 0.12.0-M2