hugo: create tempfiles in a dedicated temporary directory

Sometimes on testnodes hugo refuses to start because:

    Error: add site dependencies: create deps: failed to create file caches from configuration: mkdir /tmp/hugo_cache/default: permission denied
    Total in 0 ms

software/hugo/buildout.hash.cfg

@@ -15,7 +15,7 @@
 
 [template-cfg]
 filename = instance.cfg.in
-md5sum = 2e4bed8c7b78c410b28f8becf81da596
+md5sum = 6f5acc546a7e9ad502d5fe586a3c3072
 
 [template_nginx_conf]
 _update_hash_filename_ = templates/nginx_conf.in

software/hugo/instance.cfg.in

@@ -113,6 +113,7 @@ template =
   . ${hugo:go-environment}
   cd ${basedirectory:data}/${slap-configuration:configuration.site}
   if [ -d "public" ]; then rm -Rf public; fi
+  export TMPDIR=${hugo:path-tmp}
   hugo && hugo server --bind=${hugo:ip} --port=${hugo:hugo-port} --baseURL=${hugo-frontend:connection-secure_access} --appendPort=false  
 
 [hugo-server-service]