travis-ci: make the OSX build jobs' 'brew update' more quiet

diff --git a/builtin/show-ref.c b/builtin/show-ref.c
index 2f13f1316fadc2fc860fac75a161b47f7d11e391..ed888ffa48ce1d5ef80859b8f5b3bf1720e49abd 100644 (file)
--- a/builtin/show-ref.c
+++ b/builtin/show-ref.c
@@ -151,6 +151,7 @@ static int hash_callback(const struct option *opt, const char *arg, int unset)
 static int exclude_existing_callback(const struct option *opt, const char *arg,
                                     int unset)
 {
+       BUG_ON_OPT_NEG(unset);
        exclude_arg = 1;
        *(const char **)opt->value = arg;
        return 0;