tests: fix init subcmd after url change

My recent 401c6f072564966437a74dc2f33280a85d79dc84 ("init: make
--manifest-url flag optional") commit broke the unittest.

Change-Id: I19ad0e8c8cbb84ab5474ebc370e00acfe957e136
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/298223
Reviewed-by: Raman Tenneti <rtenneti@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/tests/test_subcmds_init.py b/tests/test_subcmds_init.py
index 3a5ca3c..af4346d 100644
--- a/tests/test_subcmds_init.py
+++ b/tests/test_subcmds_init.py
@@ -38,7 +38,7 @@
     """Check invalid command line options."""
     ARGV = (
         # Too many arguments.
-        ['asdf'],
+        ['url', 'asdf'],
 
         # Conflicting options.
         ['--mirror', '--archive'],