It occurred to me that Hubert Feyrer wrote in gmane.os.netbsd.devel.packages:
>
> On Thu, 8 Sep 2005, Martijn van Buul wrote:
>> 1) It assumes that /var/db/pkg/*/+REQUIRED_BY is valid, but unfortunately
>>   this is cannot be guaranteed, especially when 'make replace' has ever
>>   been used, as it effectively zaps the +REQUIRED_BY files.
>
> This seems wrong. At least last time i looked at the 'replace' target, it 
> moved the +REQUIRED_BY file aside to be able to pkg_delete the pkg, but 
> then move it back.

I stand corrected, but:

> My guess for the real problem at hands is that for either direction of 
> dependencies ("up" using +REQUIRED_BY or "down" using @depends lines and 
> whatnot in +CONTENTS files), they only give data for one level, and care 
> needs to be taken to walk the tree recursively.

kdelibs depends directly on pcre, and pcre's +REQUIRED_BY lists kdelibs -
at least on my system. So apperently Geert's pcre*/+REQUIRED_BY *did*
get gobbled up somehow.