[MEDIUM] checks: set server state to one state from failure when leaving maintenance

When we're enabling a server again (unix CLI or stats interface), we must not mark
it completely up because it can take a while before a failure is detected. So we
mark it one step above failure, which means it's up but will be marked down upon
first failure.
(cherry picked from commit 83c3e06452457ed5660fc814cbda5bf878bf19a2)
diff --git a/src/proto_http.c b/src/proto_http.c
index 0cbfef2..3003e5d 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2931,6 +2931,7 @@
 						if ((sv->state & SRV_MAINTAIN)) {
 							/* Already in maintenance, we can change the server state */
 							set_server_up(sv);
+							sv->health = sv->rise;	/* up, but will fall down at first failure */
 							s->data_ctx.stats.st_code = STAT_STATUS_DONE;
 						}
 						break;