Don't add extra quotation marks in scripted commands

Scripted automatically adding quotation marks when an argument contains
spaces breaks arguments that already were wrapped in quotations. The
scripted test should be responsible for its own escaping. Since this is
part of scripted-sbt-redux, we don't have to worry about downstream
builds relying on the old escaping behavior.

sbt/src/sbt-test/tests/arguments/build.sbt

@@ -2,8 +2,16 @@ val scalatest = "org.scalatest" %% "scalatest" % "3.0.5"
 
 ThisBuild / scalaVersion := "2.12.10"
 
+val foo = settingKey[Seq[String]]("foo")
+val checkFoo = inputKey[Unit]("check contents of foo")
+
 lazy val root = (project in file("."))
   .settings(
+    foo := Nil,
+    checkFoo := {
+      val arguments = Def.spaceDelimited("").parsed.mkString(" ")
+      assert(foo.value.contains(arguments))
+    },
     libraryDependencies += scalatest % Test,
     // testOptions in Test += Tests.Argument(TestFrameworks.ScalaTest, "-f", "result.txt", "-eNDXEHLO")
     testOptions in Configurations.Test ++= {

sbt/src/sbt-test/tests/arguments/test

@@ -26,3 +26,7 @@ $ touch failure3
 $ delete failure3
 
 > set Compile / scalacOptions += "-Xfatal-warnings"
+
+> set foo += "an argument with spaces"
+
+> checkFoo an argument with spaces

scripted-sbt-redux/src/main/scala/sbt/scriptedtest/SbtHandler.scala

@@ -27,7 +27,7 @@ final class SbtHandler(remoteSbtCreator: RemoteSbtCreator) extends StatementHand
 
   def apply(command: String, arguments: List[String], i: Option[SbtInstance]): Option[SbtInstance] =
     onSbtInstance(i) { (_, server) =>
-      send((command :: arguments.map(escape)).mkString(" "), server)
+      send((command :: arguments).mkString(" "), server)
       receive(s"$command failed", server)
     }
 
@@ -80,12 +80,4 @@ final class SbtHandler(remoteSbtCreator: RemoteSbtCreator) extends StatementHand
     catch { case _: SocketException => throw new TestFailed("Remote sbt initialization failed") }
     p
   }
-
-  // if the argument contains spaces, enclose it in quotes, quoting backslashes and quotes
-  def escape(argument: String) = {
-    import java.util.regex.Pattern.{ quote => q }
-    if (argument.contains(" "))
-      "\"" + argument.replaceAll(q("""\"""), """\\""").replaceAll(q("\""), "\\\"") + "\""
-    else argument
-  }
 }