Do not generate remote target when replication service is disabled

When replication service was disabled, the replication.config was still
generating a remote target using an empty string as host.

Make remote target generation conditional to the existence of a remote
target host.

Bug: Issue 13305
Change-Id: I67a2181b7bee9cb6c069c8b76b9df1dedb155060
diff --git a/gerrit/etc/replication.config.template b/gerrit/etc/replication.config.template
index 4f22f1b..94ef52f 100644
--- a/gerrit/etc/replication.config.template
+++ b/gerrit/etc/replication.config.template
@@ -20,7 +20,7 @@
   timeout = 60
 
 
-{% if REMOTE_TARGET_URL %}
+{% if REMOTE_TARGET %}
 [remote "{{REMOTE_TARGET_URL}}"]
   url = {{ REMOTE_TARGET_URL }}
   adminUrl = {{ REMOTE_ADMIN_TARGET_URL }}
diff --git a/gerrit/setup_gerrit.py b/gerrit/setup_gerrit.py
index 0a9439c..7b6759a 100755
--- a/gerrit/setup_gerrit.py
+++ b/gerrit/setup_gerrit.py
@@ -172,6 +172,7 @@
         f.write(template.render(
                 SLAVE_1_URL="git://" + SLAVE_FQDN + ":" + os.getenv('GIT_PORT') + "/${name}.git",
                 SLAVE_1_AMDIN_URL="ssh://gerrit@" + SLAVE_FQDN + ":" + os.getenv('GIT_SSH_PORT') + "/var/gerrit/git/${name}.git",
+                REMOTE_TARGET=REMOTE_TARGET,
                 REMOTE_TARGET_URL="git://" + REMOTE_TARGET + ":" + os.getenv('GIT_PORT') + "/${name}.git",
                 REMOTE_ADMIN_TARGET_URL="ssh://gerrit@" + REMOTE_TARGET + ":" + os.getenv('GIT_SSH_PORT') + "/var/gerrit/git/${name}.git",
                 ))