BUG/MINOR: promex: Don't forget to consume the request on error

When the promex applet triggers an error, for instance because the URI is
invalid, we must still take care to consume the request. Otherwise, the
error will be handled by HTTP analyzers as a server abort.

This patch must be backported as far as 2.0.

(cherry picked from commit c1b013bc61e165cd54fc3e4c538f95ba0c0104c6)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit f40463aea88b1af63f2967ae311546af70fd72e8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 1101a0504fa6f06aec433221ea1bd402d9a16e83)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 88002c7c9d0d3fd1b099d8093d83d277b2ad598d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/addons/promex/service-prometheus.c b/addons/promex/service-prometheus.c
index 7bbfc46..d31b666 100644
--- a/addons/promex/service-prometheus.c
+++ b/addons/promex/service-prometheus.c
@@ -1575,6 +1575,7 @@
 	res->flags |= CF_READ_NULL;
 	si_shutr(si);
 	si_shutw(si);
+	goto out;
 }
 
 struct applet promex_applet = {