How can my boss take rails seriously with bugs like this

next_week is not advertised to be exact. It's an approximation. That
said, this looks like a really nasty bug. Did you pass all your
tests? Your title implies that your boss is evaluating Rails based on
the kind/number of bugs present. What's the alternative? Count
unfixed bugs in .Net or any other framework? At least this is one you
might be able to fix -- it's open source.