Run builds in series

Since they I/O bound off of the same hardware, and sometimes also CPU
bound when compiling things, running them in parallel only slows
things down.

Closes: #28

pipelines/jobs/rust-xwin.yml.j2

@@ -16,30 +16,28 @@
 
 {% macro jobs() -%}
   - name: rust-xwin
+    serial: true
     plan:
       - get: repo
         trigger: true
-      - in_parallel:
+      - task: build-rust-xwin
-          fail_fast: true
+        file: repo/tasks/build-image.yml
-          steps:
+        privileged: true
-            - task: build-rust-xwin
+        vars:
-              file: repo/tasks/build-image.yml
+          context: repo/images/rust-xwin
-              privileged: true
+          target: rust-xwin
-              vars:
+          dockerfile: ''
-                context: repo/images/rust-xwin
+        output_mapping:
-                target: rust-xwin
+          image: image-rust-xwin
-                dockerfile: ''
+      - task: build-rust-xwin-ci
-              output_mapping:
+        file: repo/tasks/build-image.yml
-                image: image-rust-xwin
+        privileged: true
-            - task: build-rust-xwin-ci
+        vars:
-              file: repo/tasks/build-image.yml
+          context: repo/images/rust-xwin
-              privileged: true
+          target: rust-xwin-ci
-              vars:
+          dockerfile: ''
-                context: repo/images/rust-xwin
+        output_mapping:
-                target: rust-xwin-ci
+          image: image-rust-xwin-ci
-                dockerfile: ''
-              output_mapping:
-                image: image-rust-xwin-ci
       - in_parallel:
           steps:
             - put: image-rust-xwin

pipelines/jobs/simple-image.yml.j2

@@ -1,5 +1,6 @@
 {% macro jobs(job) -%}
   - name: {{ job.name }}
+    serial: true
     plan:
       - get: repo
         trigger: true