try again git-pull'ing if it fails

sometimes launchpad gives random HTTP errors...
Signed-off-by: Mattia Rizzolo <mapreri@ubuntu.com>

Makefile

@@ -11,7 +11,12 @@ build: full-config.ini
 
 
 update: membri
-	cd membri && git pull --ff-only
+	# Launchpad can somtimes be flaky, so be forgiving and try again
+	cd membri && \
+		set -e; for i in 1 2 3 4; do \
+			git pull --ff-only && break; \
+			sleep 5; \
+		done
 
 
 clean: