IN-117: Update environment variables to support newer versions of Jen…

…kins plugins

As part of a Jenkins upgrade and plugins reconfiguration some environments
variables stopped being present or had their name changed. Due to that, the
Jenkinsfile had to be updated and old variables have been replaced to use
the new ones.

The GIT_URL variable was removed and there is no equivalent new one, so in this
case, on the environment session, we declare a new GITHUB_REPO_URL variable which
is used in place of the old one.

Jenkinsfile

@@ -17,6 +17,7 @@ pipeline {
     WEBURL = "http://jenkins.compucorp.co.uk:8900"
     KARMA_TESTS_REPORT_FOLDER = "reports/js-karma"
     PHPUNIT_TESTS_REPORT_FOLDER = "reports/phpunit"
+    GITHUB_REPO_URL = "https://github.com/compucorp/civihr"
   }
 
   stages {
@@ -51,8 +52,8 @@ pipeline {
           sh "civibuild create ${params.CIVIHR_BUILDNAME} --type drupal-clean --civi-ver 5.3.1 --url $WEBURL"
 
           // Get target and PR branches name
-          def prBranch = env.CHANGE_BRANCH
-          def envBranch = env.CHANGE_TARGET ? env.CHANGE_TARGET : env.BRANCH_NAME
+          def prBranch = env.BRANCH_NAME
+          def envBranch = env.GITHUB_PR_TARGET_BRANCH ? env.GITHUB_PR_TARGET_BRANCH : env.BRANCH_NAME
           if (prBranch != null && prBranch.startsWith("hotfix-")) {
             envBranch = 'master'
           }
@@ -229,7 +230,7 @@ def getBuildTargetLink() {
   def link = ''
   def forPR = buildIsForAPullRequest()
 
-  link = forPR ? "<${env.CHANGE_URL}|${env.CHANGE_TITLE}>" : '<' + getRepositoryUrlForBuildBranch() + '|' + env.BRANCH_NAME + '>'
+  link = forPR ? "<${env.GITHUB_PR_URL}|${env.GITHUB_PR_TITLE}>" : '<' + getRepositoryUrlForBuildBranch() + '|' + env.BRANCH_NAME + '>'
 
   return link
 }
@@ -238,17 +239,14 @@ def getBuildTargetLink() {
  * Returns true if this build as triggered by a Pull Request.
  */
 def buildIsForAPullRequest() {
-  return env.CHANGE_URL != null
+  return env.GITHUB_PR_NUMBER != null
 }
 
 /*
  * Returns a URL pointing to branch currently being built
  */
 def getRepositoryUrlForBuildBranch() {
-  def repositoryURL = env.GIT_URL
-  repositoryURL = repositoryURL.replace('.git', '')
-
-  return repositoryURL + '/tree/' + env.BRANCH_NAME
+  return env.GITHUB_REPO_URL + '/tree/' + env.BRANCH_NAME
 }
 
 /*