version conflicts with plugins play:sbt-plugin or sbt:sbt-site (about scala-xml)

[rsinkwitz]

With one of the following lines in plugins.sbt ...
addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.8.18")
addSbtPlugin("com.typesafe.sbt" % "sbt-site" % "1.4.1")

I get the following error:
[error] (update) found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
[error]
[error] * org.scala-lang.modules:scala-xml_2.12:2.1.0 (early-semver) is selected over {1.2.0, 1.1.1, 1.0.6}
[error] +- org.scoverage:scalac-scoverage-reporter_2.12:2.0.5 (depends on 2.1.0)
[error] +- ws.unfiltered:unfiltered_2.12:0.9.1 (depends on 1.0.6)
[error] +- org.scala-lang:scala-compiler:2.12.16 (depends on 1.0.6)
[error] +- org.foundweekends:knockoff_2.12:0.8.6 (depends on 1.0.6)
[error] +- com.typesafe.sbt:sbt-native-packager:1.5.2 (scalaVersion=2.12, sbtVersion=1.0) (depends on 1.1.1
[error] +- com.typesafe.play:twirl-api_2.12:1.5.1 (depends on 1.2.0)

To reproduce, add the two (or only one) above lines into plugins.sbt of the example project "sbt-scoverage-samples-main".

[ckipp01]

Duplicate of #469, #463, #461.

Please search for your issue before opening a new one. You can see more context and a workaround in scala/bug#12632.