Header files in Perl packages

[Jason L Tibbitts III]

Some Perl packages install header files deep into the internal Perl
directory hierarchy.  I guess these are used for something internal to
Perl.  Some packages which do this are perl-PDL, Gtk-Perl, perl-DBI
(and now perl-cairo,
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=187799).

The packaging guidelines state:

 - MUST: Header files or static libraries must be in a -devel package.

but it seems pointless to put two header files in a separate -devel
package when they aren't intended to be included from user-written
code.  I suppose it's possible that Perl needs to have them present to
run.

Is this situation a valid exception to the above MUST?

 - J<