Dockerfile: install helpdesk via git get-app (local-path parsing broken in bench)

Dockerfile

@@ -63,9 +63,12 @@ WORKDIR ${BENCH_DIR}
 # telephony is a hard frappe-dependency of helpdesk (pyproject).
 RUN bench get-app --skip-assets https://github.com/frappe/telephony
 
-# helpdesk itself, from THIS build context (the hanzoai/helpdesk fork).
-COPY --chown=frappe:frappe . /home/frappe/helpdesk-src
-RUN bench get-app /home/frappe/helpdesk-src
+# helpdesk itself, from the hanzoai/helpdesk fork (this repo). bench get-app
+# wants a git remote (local-path parsing is broken in this bench), so pin the
+# branch being built.
+ARG HELPDESK_REPO=https://github.com/hanzoai/helpdesk
+ARG HELPDESK_BRANCH=blue/hanzo-deploy
+RUN bench get-app helpdesk ${HELPDESK_REPO} --branch ${HELPDESK_BRANCH}
 
 # Build all frontend assets (frappe desk + helpdesk SPA).
 RUN bench build --production