Here is a diff to fix the Parallel::Prefork build with Perl 5.28.
'make test' passes.
Charlène.
Index: Makefile
===================================================================
RCS file: /cvs/ports/devel/p5-Parallel-Prefork/Makefile,v
retrieving revision 1.7
diff -u -p -u -p -r1.7 Makefile
--- Makefile 2 Sep 2016 23:00:15 -0000 1.7
+++ Makefile 27 Jan 2019 21:58:08 -0000
@@ -4,6 +4,7 @@ COMMENT = simple prefork server framewor
DISTNAME = Parallel-Prefork-0.18
CATEGORIES = devel
+REVISION = 0
# Perl
PERMIT_PACKAGE_CDROM = Yes
Index: patches/patch-Makefile_PL
===================================================================
RCS file: patches/patch-Makefile_PL
diff -N patches/patch-Makefile_PL
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-Makefile_PL 27 Jan 2019 21:58:08 -0000
@@ -0,0 +1,10 @@
+$OpenBSD$
+Fix for perl 5.26.0+ (no . in @inc by default)
+Index: Makefile.PL
+--- Makefile.PL.orig
++++ Makefile.PL
+@@ -1,3 +1,4 @@
++BEGIN { push @INC, '.'; }
+ use inc::Module::Install;
+
+ all_from 'lib/Parallel/Prefork.pm';
