Partial sync fetch-sphinx-tarball with fetch-sphinx-output

Add and use variable sphinx_output_dir as it's used in
fetch-sphinx-output.

Change-Id: I3fa7b1982463816d16ca6515edffb9e73b8cdbe5

roles/fetch-sphinx-tarball/README.rst

@@ -12,6 +12,12 @@ archive into the log root for viewing.
    Directory relative to zuul_work_dir where build output should be
    found.
 
+.. zuul:rolevar:: sphinx_output_dir
+   :default: html
+
+   Directory relative to sphinx_build_dir where sphinx output will be
+   put.
+
 .. zuul:rolevar:: zuul_work_dir
    :default: {{ zuul.project.src_dir }}
 

roles/fetch-sphinx-tarball/defaults/main.yaml

@@ -1,3 +1,4 @@
 ---
 zuul_work_dir: "{{ zuul.project.src_dir }}"
 sphinx_build_dir: doc/build
+sphinx_output_dir: "html"

roles/fetch-sphinx-tarball/tasks/html.yaml

@@ -5,7 +5,7 @@
   register: html_archive
 
 - name: Archive HTML
-  command: "tar -f {{ html_archive.path }} -C {{ zuul_work_dir }}/{{ sphinx_build_dir }}/html -cj ."
+  command: "tar -f {{ html_archive.path }} -C {{ zuul_work_dir }}/{{ sphinx_build_dir }}/{{ sphinx_output_dir }} -cj ."
   args:
     warn: false