Fix #3496: Insert classpath before other arguments

Order expected by java command. In which all options are expected
(such as -classpath) are expected to be on the left of the first
class name.

Author: nicolasstucki

project/Build.scala

@@ -635,7 +635,7 @@ object Build {
   def insertClasspathInArgs(args: List[String], cp: String): List[String] = {
     val (beforeCp, fromCp) = args.span(_ != "-classpath")
     val classpath = fromCp.drop(1).headOption.fold(cp)(_ + ":" + cp)
-    beforeCp ::: "-classpath" :: classpath :: fromCp.drop(2)
+    "-classpath" :: classpath :: beforeCp ::: fromCp.drop(2)
   }
 
   lazy val nonBootstrapedDottyCompilerSettings = commonDottyCompilerSettings ++ Seq(

project/scripts/sbtTests

@@ -23,3 +23,12 @@ if grep -e "dotr test ok" sbtdotr2.out; then
 else
     exit -1
 fi
+echo "testing sbt dotr with no -classpath"
+pushd out/scriptedtest2
+../../project/scripts/sbt "dotr dotrtest.Test" > sbtdotr2-2.out
+if grep -e "dotr test ok" sbtdotr2-2.out; then
+    echo "output ok"
+else
+    exit -1
+fi
+popd