Merged to trunk@8719.
I’m not a fan of fixes like this, generally—but as we don’t have a spec for any of this, we don’t reject invalid expression syntax on input, and it worked before, it’s hard to argue that {$HP$} is wrong, and this change should minimize breakage. I want to make sure we don’t do this kind of thing in V4.
Try 3.2.6-svn8719.