fix: preserve arguments such as --version and -n when running commands over ssh

xargs without a command runs /bin/echo per word, which interprets --version, --help, -n, -e and -E as its own options. Use printf with a NUL delimiter instead.

Closes #9120

dokku

@@ -118,7 +118,7 @@ if [[ -n "$SSH_ORIGINAL_COMMAND" ]]; then
     exit_code=$?
     set +f
   else
-    readarray -t -O "${#ssh_arg_array[@]}" ssh_arg_array < <(printf '%s' "$SSH_ORIGINAL_COMMAND" | xargs -n 1)
+    readarray -d '' -O "${#ssh_arg_array[@]}" ssh_arg_array < <(printf '%s' "$SSH_ORIGINAL_COMMAND" | xargs -r printf '%s\0')
     set -f
     $0 "${ssh_arg_array[@]}"
     exit_code=$?

tests/unit/core_2.bats

@@ -37,6 +37,14 @@ teardown() {
   assert_success
 }
 
+@test "(core) ssh arguments are passed through unchanged" {
+  run ssh "dokku@$DOKKU_DOMAIN" fakecommand --version --help -n -e -E
+  echo "output: $output"
+  echo "status: $status"
+  assert_failure
+  assert_output_contains '`fakecommand --version --help -n -e -E` is not a dokku command.'
+}
+
 @test "(core) urls (non-ssl)" {
   assert_urls "http://${TEST_APP}.${DOKKU_DOMAIN}"