Closed issue by chase-net on void-packages repository

https://github.com/void-linux/void-packages/issues/38742

Description:
### Is this a new report?

Yes

### System Info

Void 5.18.17_1 x86_64-musl GenuineIntel notuptodate hold rFFF

### Package(s) Affected

nvi-1.81.6_17

### Does a report exist for this bug with the project's home (upstream) and/or another distro?

_No response_

### Expected behaviour

Searching should match space and tab characters when using the POSIX character classes [:space:] and [:blank:].

### Actual behaviour

[:space:] and [:blank:] seem to match the [:alnum:] character class.

### Steps to reproduce

1. Start vi. `EXINIT= vi`
2. Insert some text including spaces and alphanumeric characters and return to normal mode. `ia b c d<esc>`
3. Search for the character classes [:space:] or [:blank:]. `/[[:space:]]`
4. Cycle through matches with `n`.