Fetch Dotty nightlies correctly

Author: anatoliykmetyuk

sbt-scala3/src/dotty/tools/sbtplugin/DottyPlugin.scala

@@ -35,7 +35,14 @@ object DottyPlugin extends AutoPlugin {
 
         // get latest nightly version from maven
         def fetchSource(version: String): (scala.io.BufferedSource, String) =
-          try Source.fromURL(s"https://repo1.maven.org/maven2/org/scala-lang/scala3-compiler_$version/maven-metadata.xml") -> version
+          try {
+            val url =
+              if (version.startsWith("0"))
+                s"https://repo1.maven.org/maven2/ch/epfl/lamp/dotty-compiler_$version/maven-metadata.xml"
+              else
+                s"https://repo1.maven.org/maven2/org/scala-lang/scala3-compiler_$version/maven-metadata.xml"
+            Source.fromURL(url) -> version
+          }
           catch { case t: java.io.FileNotFoundException =>
             val major :: minor :: Nil = version.split('.').toList
             if (minor.toInt <= 0) throw t