Merge branch 'jk/shell-no-repository-that-begins-with-dash' into maint-2.4

* jk/shell-no-repository-that-begins-with-dash:
  shell: disallow repo names beginning with dash
diff --git a/shell.c b/shell.c
index ace62e4..c3bf8ec 100644
--- a/shell.c
+++ b/shell.c
@@ -13,7 +13,7 @@
 	const char *my_argv[4];
 
 	setup_path();
-	if (!arg || !(arg = sq_dequote(arg)))
+	if (!arg || !(arg = sq_dequote(arg)) || *arg == '-')
 		die("bad argument");
 	if (!starts_with(me, "git-"))
 		die("bad command");