nix: Simplify with_tmp_db

nix/tools/withTools.nix

@@ -60,15 +60,9 @@ let
 
         log "Starting the database cluster..."
         # Instead of listening on a local port, we will listen on a unix domain socket.
-        pg_ctl -l "$tmpdir/db.log" start -o "-F -c listen_addresses=\"\" -k $PGHOST" \
+        pg_ctl -l "$tmpdir/db.log" -w start -o "-F -c listen_addresses=\"\" -k $PGHOST" \
           >> "$setuplog"
 
-        log "Waiting for the database cluster to be ready..."
-        # Waiting is required for older versions of Postgres (< 10).
-        until pg_isready >> "$setuplog"; do
-          sleep 0.1
-        done
-
         stop () {
           log "Stopping the database cluster..."
           pg_ctl stop -m i >> "$setuplog"