Fix name mangling for nested classes

core/src/main/scala/com/typesafe/tools/mima/core/MimaUnpickler.scala

@@ -44,9 +44,10 @@ object MimaUnpickler {
         def withOwner(cls: ClassInfo) = {
           val nme1 = cls.bytecodeName
           val nme2 = symbolInfo.name
+          val nme3 = if (nme2.startsWith(nme1)) nme2.substring(nme2.lastIndexOf('$') + 1) else nme2
           val conc = if (nme1.endsWith("$")) "" else "$"
           val suff = if (symbolInfo.isModuleOrModuleClass) "$" else ""
-          val name = nme1 + conc + nme2 + suff
+          val name = nme1 + conc + nme3 + suff
           clazz.owner.classes(name)
         }
         val fallback = if (symbolInfo.isModuleOrModuleClass) clazz.moduleClass else clazz

functional-tests/src/test/unpickling-name-mangling-ok/app/App.scala

@@ -0,0 +1,3 @@
+object App {
+  def main(args: Array[String]): Unit = ()
+}

functional-tests/src/test/unpickling-name-mangling-ok/v1/A.scala

@@ -0,0 +1,3 @@
+class Foo {
+  private[Foo] object Bar
+}

functional-tests/src/test/unpickling-name-mangling-ok/v2/A.scala

@@ -0,0 +1,3 @@
+class Foo {
+  private[Foo] object Bar
+}