Can't believe I missed this. Should have been part
of the Do Nothing Gracefully cleanup.
You cannot use [string replace] to insert a substring
without at the same time taking at least on character
% string replace abcde 1 0 h
Instead of the result any sane programmer would
In particular, the useful case of prepending is not
Recategorize to a Feature Request if you must. (This
misfeature is documented, FFS). But it's so boneheaded
it looks like a bug to me.