Regression in presentation compiler: imported symbol not found

[scabug]

Presentation compiler sometimes does not see imported symbols. For example, when I load following two files into the presentation compiler:

// Prestest.scala
package prestest

object Prestest {
  trait Root {
    def meth = 5
  }
}

// ops.scala
package com.whatever

//import prestest.Prestest.Root

object Utils {
  import prestest.Prestest.Root

  implicit class rootOps(root: Root) {
    def implicitMethod: Int = 42
  }
}

I get the following error when typechecking the second file:

ops.scala:10: error: not found: type Root
  implicit class rootOps(root: Root) {
                               ^

The problem disappears when I move the import statement outside of Utils object.

I did a git-bisect and found out that the regression was introduced in 7664e25eed8ae4547f1cfd774b62a7b6a4baf8b5 (fix for #8941).

Here's a full source of test case that I was running:

import scala.reflect.internal.util.BatchSourceFile
import scala.tools.nsc.{interactive, Settings}
import scala.tools.nsc.reporters.ConsoleReporter

object Test {

  def main(args: Array[String]) {
    val settings = new Settings
    settings.usejavacp.value = true
    val reporter = new ConsoleReporter(settings)

    val iglobal = new interactive.Global(settings, reporter)
    import iglobal._

    def getOrThrow[T](resp: Response[T]) = resp.get match {
      case Left(res) => res
      case Right(t) => throw t
    }

    def load(sourceFile: BatchSourceFile) = {
      val resp = new Response[Tree]
      askLoadedTyped(sourceFile, resp)
      getOrThrow(resp)
    }

    val prestestSrc = new BatchSourceFile("Prestest.scala",
      """
        |package prestest
        |
        |object Prestest {
        |  trait Root {
        |    def meth = 5
        |  }
        |}
        |
      """.stripMargin
    )

    load(prestestSrc)

    val opsSrc = new BatchSourceFile("ops.scala",
      """
        |package com.whatever
        |
        |//import prestest.Prestest.Root
        |
        |object Utils {
        |
        |  import prestest.Prestest.Root
        |
        |  implicit class rootOps(root: Root) {
        |    def implicitMethod: Int = 42
        |  }
        |
        |}
      """.stripMargin)

    load(opsSrc)

    if(reporter.hasErrors) {
      throw new Exception("There were errors")
    }
  }

}

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-9283?orig=1
Reporter: @ghik
Affected Versions: 2.11.5, 2.11.6
See #8941