Mr Swinney has been a naughty boy. Allegedly, he failed to tell the parliament that the Scottish administration had refused to pay HMRC to maintain or upgrade the computer system which enables the plus or minus three pence variation of the income tax rate. Cue much huffing and puffing on the part of the opposition parties.
I find it hard to take seriously this storm in a teacup. Neither Labour nor the SNP has ever seriously proposed exercising the power to vary the rate and there is absolutely no sign that either would have proposed to do so following next year's election. (Which makes me wonder why Calman is being introduced, although that is a separate argument.)
So rap Mr S's knockles, tell him to behave more respectfully in future, and move on. There must be more important issues for the parliament to get excited about.