ClassCast on sbt publish

[analytically]

When I run sbt clean jacoco:cover publish I always end up with:

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
    at org.apache.ivy.core.settings.IvySettings.addAllVariables(IvySettings.java:589)
    at org.apache.ivy.core.settings.IvySettings.addAllVariables(IvySettings.java:583)
    at org.apache.ivy.core.settings.IvySettings.addSystemProperties(IvySettings.java:303)
    at org.apache.ivy.core.settings.IvySettings.<init>(IvySettings.java:298)
    at org.apache.ivy.core.settings.IvySettings.<init>(IvySettings.java:218)
    at sbt.IvySbt.sbt$IvySbt$$settings$lzycompute(Ivy.scala:66)
    at sbt.IvySbt.sbt$IvySbt$$settings(Ivy.scala:64)
    at sbt.IvySbt.ivyLockFile$lzycompute(Ivy.scala:92)
    at sbt.IvySbt.ivyLockFile(Ivy.scala:92)
    at sbt.IvySbt.withDefaultLogger(Ivy.scala:60)
    at sbt.IvySbt.withIvy(Ivy.scala:101)
    at sbt.IvySbt.withIvy(Ivy.scala:97)
    at sbt.IvySbt$Module.withModule(Ivy.scala:116)
    at sbt.IvyActions$.makePom(IvyActions.scala:68)
    at sbt.Classpaths$$anonfun$32.apply(Defaults.scala:946)
    at sbt.Classpaths$$anonfun$32.apply(Defaults.scala:946)
    at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
    at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:42)

Just sbt clean publish works fine, just sbt clean jacoco:cover as well.

SBT 0.13.2 and 0.13.5, tried various things like setting publishMavenStyle to false.