fix : windows list_jobs : trying to get id of un-existing merge requests led to pipeline failure

.gitlab/ci/download/select_jobs.gitlab-ci.yml

@@ -316,10 +316,12 @@
         Write-Host "****************************************************************************************************************************"
         Write-Host "Retrieving regular pipelines from $API_URL/projects/$DEP_ID/pipelines?ref=$BRANCH_TO_PULL"
         $PIPELINES=$(Invoke-RestMethod -Uri "$API_URL/projects/$DEP_ID/pipelines?ref=$BRANCH_TO_PULL" -Method Get)
-        Write-Host "Retrieving Merge requests pipelines from $API_URL/projects/$DEP_ID/merge_requests?source_branch=$BRANCH_TO_PULL"
-        $MR_ID=(Invoke-RestMethod -Uri "$API_URL/projects/$DEP_ID/merge_requests?source_branch=$BRANCH_TO_PULL" -Method Get)[0].iid
-        $MR_PIPELINES=(Invoke-RestMethod -Uri "$API_URL/projects/$DEP_ID/merge_requests/$MR_ID/pipelines" -Method Get)
-        $PIPELINES+=$MR_PIPELINES
+        $MR_ID=(Invoke-RestMethod -Uri "$API_URL/projects/$DEP_ID/merge_requests?source_branch=$BRANCH_TO_PULL" -Method Get)
+        Write-Host "Found $($MR_ID.Count) MR with $BRANCH_TO_PULL as target branch."
+        if ( $MR_ID.Count -ne 0 ){
+            $MR_PIPELINES=(Invoke-RestMethod -Uri "$API_URL/projects/$DEP_ID/merge_requests/$MR_ID/pipelines" -Method Get)
+            $PIPELINES+=$MR_PIPELINES
+        }
         ## Sort pipelines by "updated_at" from earliest to latest and only retrieve the ones whose url contain our project namespaec.
         $PIPELINES = $PIPELINES | 
                      Where-Object { $_.web_url -match $CI_PROJECT_NAMESPACE } |