http://github.com/jenkinsci/winstone/commit/26c7de06a9be7eea8d2c959f0366b2d287d99388 changed logging framework to use java.util.logger, then level switched from (1:9) range to (Integer.MIN_VALUE:MAX_VALUE).

setting JENKINS_DEBUG_LEVEL to 5 in jenkins sysconif, expecting INFO, result in FINEST logging.

actual impact on jenkins probably was hidden by JENKINS-16952.