Fix test-salt-model-wrapper env props reading

Change-Id: I4d39efe687cce031f733d5832b517862e8cec052
diff --git a/test-salt-model-wrapper.groovy b/test-salt-model-wrapper.groovy
index 6adc720..3ef577b 100644
--- a/test-salt-model-wrapper.groovy
+++ b/test-salt-model-wrapper.groovy
@@ -115,7 +115,7 @@
 
         // Common and manual build parameters
         LinkedHashMap projectsMap = [:]
-        String distribRevision = job_env('DISTRIB_REVISION', 'nightly')
+        String distribRevision = job_env.get('DISTRIB_REVISION', 'nightly')
         ArrayList testModels = job_env.get('TEST_MODELS', 'mcp-virtual-lab,infra').split(',')
 
         stage('Check build mode') {