argparse: Fix -- regression

I was a tad overzealous there with not appending the remaining
arguments.

Weird that we didn't test it, though.

Fixes #5857.

src/builtin_argparse.cpp

@@ -634,10 +634,8 @@ static int argparse_parse_args(argparse_cmd_opts_t &opts, const wcstring_list_t
     retval = check_for_mutually_exclusive_flags(opts, streams);
     if (retval != STATUS_CMD_OK) return retval;
 
-    if (opts.stop_nonopt) {
-        for (int i = optind; argv[i]; i++) {
-            opts.argv.push_back(argv[i]);
-        }
+    for (int i = optind; argv[i]; i++) {
+        opts.argv.push_back(argv[i]);
     }
 
     return STATUS_CMD_OK;

tests/argparse.err

@@ -118,3 +118,6 @@ in function 'notargparse'
 
 ####################
 # Check for crash when last option is unknown
+
+####################
+# Checking arguments after --

tests/argparse.in

@@ -189,3 +189,9 @@ echo $_flag_a
 
 logmsg Check for crash when last option is unknown
 argparse -i b/break -- "-b kubectl get pods -l name=foo"
+
+begin
+    logmsg Checking arguments after "--"
+    argparse a/alpha -- a --alpha -- b -a
+    printf '%s\n' $argv
+end

tests/argparse.out

@@ -140,3 +140,9 @@ alpha aaaa
 
 ####################
 # Check for crash when last option is unknown
+
+####################
+# Checking arguments after --
+a
+b
+-a