Perl Finds CORE::readpipe Has No Opnumber

Zaxo has asked for the wisdom of the Perl Monks concerning the following question:

I've stumbled on an oddity that smells like a bug:

$ perl -e'print prototype "CORE::readpipe"'
Can't find an opnumber for "readpipe" at -e line 1.
$ perl -v

This is perl, v5.6.1 built for i686-linux

I get the same error with 5.8.0-RC1. In keywords.h, readpipe is assigned opnumber 158, and I don't see any unusual treatment of it in toke.c.

The readpipe function works fine. Does anybody know why this error is thrown?

After Compline,
Zaxo
nodus DCLXVIimus

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