Trying to reference the Cf category generates an error

[justinmchase]

If I use the unicode class cf:

static ref RE: Regex = Regex::new(r"^[\p{cf}]$").unwrap();

It generates this error:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regex parse error:
    ^[\p{cf}]$
      ^^^^^^
error: Unicode property not found
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
)', src/runtime/modules/unicode.rs:21:28

But I see the format is here in the code:
https://github.com/rust-lang/regex/blob/master/regex-syntax/src/unicode_tables/property_values.rs#L72

If I change the regex to be \p{Format} then it actually works. This is a little confusing to me, can someone please explain why \p{cf} doesn't work?

[BurntSushi]

This is fixed in regex 1.4.1 on crates.io. Thank you for the bug report! Good find.