dotc fails to find shared backend on first run

[DarkDimius]

Reported by @henricook

dotty git:(master) ./bin/dotc tests/pos/HelloWorld.scala
find: ‘/home/henri/.coursier/cache’: No such file or directory
The script is going to build the required jar files
Building dotty-interfaces...done
Building dotty...done
Building tests...done
To use this script please set
SCALA_LIBRARY_JAR to point to scala-library-2.11.5.jar (currently /home/henri/.ivy2/cache/org.scala-lang/scala-library/jars/scala-library-2.11.5.jar)
SCALA_REFLECT_JAR to point to scala-reflect-2.11.5.jar (currently /home/henri/.ivy2/cache/org.scala-lang/scala-reflect/jars/scala-reflect-2.11.5.jar)
SCALA_COMPILER_JAR to point to scala-compiler-2.11.5.jar with bcode patches (currently )
JLINE_JAR to point to jline-2.12.jar (currently /home/henri/.ivy2/cache/jline/jline/jars/jline-2.12.jar)
SBT_INTERFACE_JAR to point to interface-0.13.11.jar (currently /home/henri/.ivy2/cache/org.scala-sbt/interface/jars/interface-0.13.11.jar)
Exception in thread "main" java.lang.NoClassDefFoundError: scala/tools/nsc/backend/jvm/BCodeSyncAndTry
at dotty.tools.backend.jvm.GenBCode.run(GenBCode.scala:48)
at dotty.tools.dotc.core.Phases$Phase
at dotty.tools.dotc.core.Phases$Phase
at scala.collection.immutable.List.map(List.scala:273)
at dotty.tools.dotc.core.Phases$Phase$class.runOn(Phases.scala:274)
at dotty.tools.backend.jvm.GenBCode.runOn(GenBCode.scala:39)
...
dotty git:(master) ./bin/dotc tests/pos/HelloWorld.scala
➜ dotty git:(master) 

Note those lines:

SCALA_COMPILER_JAR to point to scala-compiler-2.11.5.jar with bcode patches (currently )
Exception in thread "main" java.lang.NoClassDefFoundError: scala/tools/nsc/backend/jvm/BCodeSyncAndTry