-Ycheck:labelDefs failure

[odersky]

Doing

dotc pos/desugar.scala -Ycheck:labeLDefs

I get:

*** error while checking after phase labelDef ***
exception occurred while compiling desugar.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: desugar$.desugar$fors$<local fors$>$$$anonfun$$init$$2 name is invalid on jvm
at scala.Predef$.assert(Predef.scala:165)
at dotty.tools.dotc.transform.TreeChecker$Checker$$anonfun$typedDefDef$1$$anonfun$apply$3.apply(TreeChecker.scala:285)
at dotty.tools.dotc.transform.TreeChecker$Checker$$anonfun$typedDefDef$1$$anonfun$apply$3.apply(TreeChecker.scala:284)

This also raises the question, why did the checkin tests not detect this? Mu local junit test in Eclipse
fails with the same error becuase -Ycheck:labelDefs is now on.