Change node 'image' to 'label'

We are keeping the 'label' terminology in nodepool, and since that
is actually what zuul asks for, use that terminology here to avoid
confusion.

Change-Id: I5f5f1cd041b6dbd80a75af66fe02520f3eb32151
diff --git a/tests/fixtures/layouts/disable_at.yaml b/tests/fixtures/layouts/disable_at.yaml
index 2956ebf..8e352d8 100644
--- a/tests/fixtures/layouts/disable_at.yaml
+++ b/tests/fixtures/layouts/disable_at.yaml
@@ -19,7 +19,7 @@
     name: project-test1
     nodes:
       - name: controller
-        image: image1
+        label: label1
 
 - project:
     name: org/project
diff --git a/tests/fixtures/layouts/dont-ignore-ref-deletes.yaml b/tests/fixtures/layouts/dont-ignore-ref-deletes.yaml
index aee5ac6..6a05fe6 100644
--- a/tests/fixtures/layouts/dont-ignore-ref-deletes.yaml
+++ b/tests/fixtures/layouts/dont-ignore-ref-deletes.yaml
@@ -11,7 +11,7 @@
     name: project-post
     nodes:
       - name: static
-        image: ubuntu-xenial
+        label: ubuntu-xenial
 
 - project:
     name: org/project
diff --git a/tests/fixtures/layouts/idle.yaml b/tests/fixtures/layouts/idle.yaml
index ff33842..60f8ed1 100644
--- a/tests/fixtures/layouts/idle.yaml
+++ b/tests/fixtures/layouts/idle.yaml
@@ -9,13 +9,13 @@
     name: project-bitrot-stable-old
     nodes:
       - name: static
-        image: ubuntu-xenial
+        label: ubuntu-xenial
 
 - job:
     name: project-bitrot-stable-older
     nodes:
       - name: static
-        image: ubuntu-trusty
+        label: ubuntu-trusty
 
 - project:
     name: org/project
diff --git a/tests/fixtures/layouts/no-timer.yaml b/tests/fixtures/layouts/no-timer.yaml
index c8ced62..12eaa35 100644
--- a/tests/fixtures/layouts/no-timer.yaml
+++ b/tests/fixtures/layouts/no-timer.yaml
@@ -27,13 +27,13 @@
     name: project-bitrot-stable-old
     nodes:
       - name: static
-        image: ubuntu-xenial
+        label: ubuntu-xenial
 
 - job:
     name: project-bitrot-stable-older
     nodes:
       - name: static
-        image: ubuntu-trusty
+        label: ubuntu-trusty
 
 - project:
     name: org/project
diff --git a/tests/fixtures/layouts/repo-deleted.yaml b/tests/fixtures/layouts/repo-deleted.yaml
index a33da77..95d11bb 100644
--- a/tests/fixtures/layouts/repo-deleted.yaml
+++ b/tests/fixtures/layouts/repo-deleted.yaml
@@ -40,14 +40,14 @@
     name: project-test1
     nodes:
       - name: controller
-        image: image1
+        label: label1
 
 - job:
     name: project-test1
     branches: stable
     nodes:
       - name: controller
-        image: image2
+        label: label2
 
 - job:
     name: project-test2
diff --git a/tests/fixtures/layouts/smtp.yaml b/tests/fixtures/layouts/smtp.yaml
index 8f53d02..fd91d36 100644
--- a/tests/fixtures/layouts/smtp.yaml
+++ b/tests/fixtures/layouts/smtp.yaml
@@ -46,14 +46,14 @@
     name: project-test1
     nodes:
       - name: controller
-        image: image1
+        label: label1
 
 - job:
     name: project-test1
     branches: stable
     nodes:
       - name: controller
-        image: image2
+        label: label2
 
 - job:
     name: project-test2
diff --git a/tests/fixtures/layouts/timer.yaml b/tests/fixtures/layouts/timer.yaml
index 95199e7..883c32e 100644
--- a/tests/fixtures/layouts/timer.yaml
+++ b/tests/fixtures/layouts/timer.yaml
@@ -28,13 +28,13 @@
     name: project-bitrot-stable-old
     nodes:
       - name: static
-        image: ubuntu-xenial
+        label: ubuntu-xenial
 
 - job:
     name: project-bitrot-stable-older
     nodes:
       - name: static
-        image: ubuntu-trusty
+        label: ubuntu-trusty
 
 - project:
     name: org/project