releaseVersion <<= (releaseVersionBump)( bumper=>{
   ver => Version(ver)
          .map(_.withoutQualifier)
          .map(_.bump(bumper).string).getOrElse(versionFormatError)
})

releaseVersion := {
  ver => Version(ver)
    .map(_.withoutQualifier.string)
    .getOrElse(versionFormatError)
  }