st.from_regex(re.compile("[\u0130_]", re.IGNORECASE)) triggers internal error

[Zac-HD]

\u0130, Latin Capital Letter I with Dot Above, lower-cases to i\u0307; and in turn if we have this in a regex character set we eventually trigger an internal error by passing it to ord() (which requires single-character strings).

I suspect that this is symptomatic of more general mishandling of length-changing case handling and will investigate.