"brown-paper-bag bug"

Definition: brown-paper-bag bug: n. A bug in a public software release that is so embarrassing that the author notionally wears a brown paper bag over his head for a while so he won't be recognized on the net. Entered popular usage after the early-1999 release of the first Linux 2.2, which had one. The phrase was used in Linus Torvalds's apology posting. From Jargon Dictionary

* Linux/Unix/Computing Glossary