static-docs: use target from fileserver

The "target_dir" fact is set only for localhost, so can't be
referenced below when running the synchronize on the fileserver.

fileserver.path and static_target should be set globally and can be
referenced in the synchronize step.  Move the master branch check
out and earlier.

Change-Id: Ie9f73df453abb7321950f12b34dcc911b950d630

playbooks/static-docs/promote.yaml

@@ -6,6 +6,10 @@
       when: "zuul.branch is not defined"
       fail:
         msg: "This playbook must be run in a branch-based pipeline (e.g., 'promote')."
+    - name: Check target branch is master
+      when: "zuul.branch != 'master'"
+      fail:
+        msg: "This job should be only run on the master branch."
     - name: Download docs archive
       include_role:
         name: download-artifact
@@ -34,14 +38,6 @@
       command: "mv {{ item.path }} {{ zuul.executor.work_root }}/docs"
       with_items: "{{ pdf_files.files }}"
       when: pdf_files.matched > 0
-    - name: Set target directory if master
-      when: "zuul.branch == 'master'"
-      set_fact:
-        target_dir: "{{ fileserver.path }}/{{ static_target }}/"
-    - name: Set target directory if not master
-      when: "zuul.branch != 'master'"
-      fail:
-        msg: "This jobs should be only run on master branch."
     - name: Add fileserver
       include_role:
         name: add-fileserver
@@ -52,4 +48,4 @@
     - name: Upload docs to static site
       synchronize:
         src: "{{ zuul.executor.work_root }}/docs/"
-        dest: "{{ target_dir }}"
+        dest: "{{ fileserver.path }}/{{ static_target }}"