ci: identify runner in each stage

contrib/ci/Jenkinsfile

@@ -11,12 +11,14 @@ pipeline {
 				stage('lint-lua') {
 					agent { label 'gluon-docker' }
 					steps {
+						sh label: 'Identify runner', script: 'echo $SLAVE_NAME'
 						sh 'make lint-lua'
 					}
 				}
 				stage('lint-sh') {
 					agent { label 'gluon-docker-v1' }
 					steps {
+						sh label: 'Identify runner', script: 'echo $SLAVE_NAME'
 						sh 'make lint-sh'
 					}
 				}
@@ -25,12 +27,14 @@ pipeline {
 		stage('docs') {
 			agent { label 'gluon-docker' }
 			steps {
+				sh label: 'Identify runner', script: 'echo $SLAVE_NAME'
 				sh 'make -C docs html'
 			}
 		}
 		stage('build') {
 			agent { label 'gluon-docker' }
 			steps {
+				sh label: 'Identify runner', script: 'echo $SLAVE_NAME'
 				sh 'make update'
 				sh 'test -d /dl_cache && ln -s /dl_cache openwrt/dl || true'
 				sh 'make -j$(nproc) V=s'
@@ -43,6 +47,7 @@ pipeline {
 				TMUX = "notmux"
 			}
 			steps {
+				sh label: 'Identify runner', script: 'echo $SLAVE_NAME'
 				unstash 'gluon-x86-64-factory'
 				sh label: 'Unpack image', script: 'gunzip -cd ./output/images/factory/*x86-64*.img.gz > ./image.img'
 				sh label: 'Print python environment', script: 'python3 -m pip freeze'