[1.2.x] on Scala 2.11 scala-parser-combinators 1.1.2 on test requires forking

[eed3si9n]

Reported originally by @Philippus as scala/scala-parser-combinators#197

steps

Philippus/bump#8

problem

Philippus/bump#8 fails with the following exception in scala 2.11:

SemVer.nextStable removes pre-release information if available: Exception raised on property evaluation.
[info] > Exception: java.lang.AbstractMethodError: nl.gn0s1s.bump.SemVerParser$.scala$util$parsing$combinator$Parsers$$lastNoSuccessVar()Lscala/util/DynamicVariable;

expectation

No failure.

workarond

Test / fork := true

notes

This is a variation of
#3405
scala/scala-xml#195
sbt/zinc#505

[eed3si9n]

So basically sbt/zinc#505 fixed the bug for run

   def makeLoader(classpath: Seq[File], instance: ScalaInstance): ClassLoader =
-    filterByClasspath(classpath, makeLoader(classpath, instance.loader, instance))
+    filterByClasspath(classpath, makeLoader(classpath, instance.loaderLibraryOnly, instance))

but didn't for test it seems.

https://github.com/sbt/sbt/blob/v1.2.8/testing/src/main/scala/sbt/TestFramework.scala#L258

    val dual = new DualLoader(
      scalaInstance.loader,

[SethTisue]

/cc @ashawley, since scala-xml is affected as well (on 2.11 and 2.12)

[eed3si9n]

@eatkins We still have this problem because ScalaInstance loader for Scala 2.11 probably is bringing in parser combinator - http://repo1.maven.org/maven2/org/scala-lang/scala-compiler/2.11.12/scala-compiler-2.11.12.pom
I think the bottom layer needs to be a Scala Library only loader.