check if letsencrypt cert is already present

debian/changelog

@@ -6,6 +6,7 @@ gitlab (8.5.8+dfsg-3) UNRELEASED; urgency=medium
   * Use embedded copy of fuzzaldrin-plus (See #814871 for more details)
   * Bring back db check in postinst (initialize the db only if it is empty)
   * Choose unicode for db encoding (fixes wiki creation error)
+  * Don't run letsencrypt if certificate is already present
 
  -- Pirate Praveen <praveen@debian.org>  Sun, 03 Apr 2016 17:41:28 +0530
 

debian/postinst

@@ -97,6 +97,10 @@ case "$1" in
         # Check if letsencrypt option is selected
         db_get gitlab/letsencrypt
         if [ "${RET}" = "true" ]; then
+	# Check if certificate is already present
+	  if [ -e /etc/letsencrypt/live/${GITLAB_HOST}/fullchain.pem ]; then
+	    echo "Let's encrypt certificate already present."
+	  else
             ln -sf /etc/letsencrypt/live/${GITLAB_HOST}/fullchain.pem \
             /etc/gitlab/ssl/gitlab.crt
             ln -sf /etc/letsencrypt/live/${GITLAB_HOST}/privkey.pem \
@@ -106,6 +110,7 @@ case "$1" in
 	    letsencrypt -d ${GITLAB_HOST} certonly
 	  fi
         fi
+      fi
 
       if test -f ${nginx_conf_example}; then
         sed -e "s/YOUR_SERVER_FQDN/${GITLAB_HOST}/"\