Add ability to run cookiecutter tests against packaging/sources/reclass repo

Add ability to test patches to packaging/sources/reclass repo

Change-Id: Icd2d0c78ff18ac90791a935fc9e58935bb9f3af6
Related-bug: PROD-21847
diff --git a/test-cookiecutter-reclass-chunk.groovy b/test-cookiecutter-reclass-chunk.groovy
index b1266a3..852cabf 100644
--- a/test-cookiecutter-reclass-chunk.groovy
+++ b/test-cookiecutter-reclass-chunk.groovy
@@ -34,6 +34,9 @@
                     'dockerContainerName': extraVars.DockerCName,
                     'testContext': extraVars.modelFile
                 ]
+                if (extraVars.useExtraRepos) {
+                    config['extraReposYaml'] = extraVars.extraReposYaml
+                }
                 saltModelTesting.testNode(config)
             } catch (Throwable e) {
                 // If there was an error or exception thrown, the build failed