fix: #79: unable to mark effectively flarum installed (#80)

rootfs/usr/local/bin/startup

@@ -75,7 +75,7 @@ if [ ! -e '/etc/nginx/flarum/custom-vhost-flarum.conf' ]; then
 fi
 
 # if installation was performed before
-if [ -e '/flarum/app/public/assets/rev-manifest.json' ]; then
+if [ -e '/flarum/app/public/assets/rev-manifest.json' ] || [ -e '/flarum/app/public/assets/._flarum-installed.lock' ] ; then
   echo "[INFO] Flarum already installed, init app..."
 
   sed -i -e "s|<DEBUG>|${DEBUG}|g" \
@@ -127,7 +127,8 @@ else
          -e "s|<FLARUM_TITLE>|${FLARUM_TITLE}|g" /flarum/app/config.yml
 
   # Install flarum
-  su-exec "${UID}:${GID}" php /flarum/app/flarum install --file=/flarum/app/config.yml
+  su-exec "${UID}:${GID}" php /flarum/app/flarum install --file=/flarum/app/config.yml &&
+    touch /flarum/app/public/assets/._flarum-installed.lock
   echo "[INFO] End of flarum installation"
 fi