Merge pull request #191 from MarkEWaite/develop/use-1.642.1

Update to next LTS version of Jenkins : 1.642.1
diff --git a/Dockerfile b/Dockerfile
index ba1e0cd..97135d3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -27,8 +27,8 @@
 
 COPY init.groovy /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy
 
-ENV JENKINS_VERSION 1.625.3
-ENV JENKINS_SHA 537d910f541c25a23499b222ccd37ca25e074a0c
+ENV JENKINS_VERSION 1.642.1
+ENV JENKINS_SHA 6a0213256670a00610a3e09203850a0fcf1a688e
 
 
 # could use ADD but this one does not check Last-Modified header