Really define gerrit_root in copy-plugin-deps role
The copy-plugin-deps role relied on an undefined variable "gerrit_root".
This caused plugins such as oauth, which have external deps, to fail the
gerrit-plugin-build job.
It was already attempted in I68ef0074b69f, but prepare-gerrit-repos role
was adapted.
Bug: Issue 13037
Change-Id: Ife5dfbcdad28777916f69081cf4d3c094b021615
diff --git a/roles/copy-plugin-deps/defaults/main.yaml b/roles/copy-plugin-deps/defaults/main.yaml
index 798daf7..80810bc 100644
--- a/roles/copy-plugin-deps/defaults/main.yaml
+++ b/roles/copy-plugin-deps/defaults/main.yaml
@@ -1 +1,3 @@
+gerrit_project_name: gerrit.googlesource.com/gerrit
gerrit_plugin: "{{ zuul.project.short_name }}"
+gerrit_root: "{{ ansible_user_dir }}/{{ zuul.projects[gerrit_project_name].src_dir }}"
