core.warnambiguousrefs: warns when "name" is used and both "name" branch and tag exists.

Signed-off-by: Junio C Hamano <junkio@cox.net>

config.c

@@ -232,6 +232,11 @@ int git_default_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.warnambiguousrefs")) {
+		warn_ambiguous_refs = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "user.name")) {
 		strncpy(git_default_name, value, sizeof(git_default_name));
 		return 0;