Use normal string parameter for now

Plugin for gitParam is not installed in the Apache Jenkins instance

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1849879 13f79535-47bb-0310-9956-ffa450edef68

jenkins/create_jobs.groovy

@@ -276,10 +276,12 @@ poijobs.each { poijob ->
 
         if (poijob.githubpr) {
             parameters {
+                /* plugin not available:
                 gitParam('sha1') {
                     description('Pull request')
                     type('BRANCH')
-                }
+                }*/
+                stringParam('sha1', 'origin/pr/9/head', 'Provide a branch-spec, e.g. origin/pr/9/head')
             }
             triggers {
                 githubPullRequest {