It won't break the log chain, because SQL doesn't know the backup's been discarded, so you will still be able to take log backups, however those log backups will be useless and you'll be unable to restore past the backup that was done to nul, because restoring log backups requires that ALL of them are present and restored in sequence.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability