add support for sbt 0.13, fixes #35

build.sbt

@@ -8,4 +8,9 @@ CrossBuilding.scriptedSettings
 
 libraryDependencies += "com.github.mdr" %% "ascii-graphs" % "0.0.3"
 
+libraryDependencies <++= scalaVersion { version =>
+  if (version startsWith "2.1") Seq("org.scala-lang" % "scala-reflect" % version % "provided")
+  else Nil
+}
+
 scalacOptions ++= Seq("-deprecation", "-unchecked")

src/main/scala-sbt-0.13/sbt/SbtDependencyGraphCompat.scala

@@ -0,0 +1,39 @@
+package sbt
+
+import net.virtualvoid.sbt.graph.Plugin._
+import Keys._
+import CrossVersion._
+
+object SbtDependencyGraphCompat {
+  /**
+   * This is copied directly from sbt/main/Defaults.java and then changed to update the UpdateConfiguration
+   * to ignore missing artifacts.
+   */
+  def ignoreMissingUpdateT =
+    ignoreMissingUpdate <<= Def.task {
+      val depsUpdated = transitiveUpdate.value.exists(!_.stats.cached)
+      val isRoot = executionRoots.value contains resolvedScoped.value
+      val s = streams.value
+      val scalaProvider = appConfiguration.value.provider.scalaProvider
+
+      // Only substitute unmanaged jars for managed jars when the major.minor parts of the versions the same for:
+      //   the resolved Scala version and the scalaHome version: compatible (weakly- no qualifier checked)
+      //   the resolved Scala version and the declared scalaVersion: assume the user intended scalaHome to override anything with scalaVersion
+      def subUnmanaged(subVersion: String, jars: Seq[File])  =  (sv: String) =>
+        (partialVersion(sv), partialVersion(subVersion), partialVersion(scalaVersion.value)) match {
+          case (Some(res), Some(sh), _) if res == sh => jars
+          case (Some(res), _, Some(decl)) if res == decl => jars
+          case _ => Nil
+        }
+      val subScalaJars: String => Seq[File] = Defaults.unmanagedScalaInstanceOnly.value match {
+        case Some(si) => subUnmanaged(si.version, si.jars)
+        case None => sv => if(scalaProvider.version == sv) scalaProvider.jars else Nil
+      }
+      val transform: UpdateReport => UpdateReport = r => Classpaths.substituteScalaFiles(scalaOrganization.value, r)(subScalaJars)
+
+      val show = Reference.display(thisProjectRef.value)
+      Classpaths.cachedUpdate(s.cacheDirectory, show, ivyModule.value, (updateConfiguration in ignoreMissingUpdate).value, transform, skip = (skip in update).value, force = isRoot, depsUpdated = depsUpdated, log = s.log)
+    }
+
+  def getTerminalWidth: Int = JLine.usingTerminal(_.getWidth)
+}