src/usr.bin/kyua breaks on manbuild.sh: Permission denied

src/usr.bin/kyua breaks on manbuild.sh: Permission denied

Example:
cd /usr/src
cat .ctm_status 
	src-cur 14430
cat .svn_revision 
	359319
uname -a
	FreeBSD lapr.js.berklix.net 13.0-CURRENT FreeBSD 13.0-CURRENT #14410: Sun Mar 15 16:28:46 CET 2020     jhs_at_lapr.js.berklix.net:/usr/src/sys/amd64/compile/LAPR.small  amd64

cd /usr/src/usr.bin/kyua ;  make
	/usr/src/contrib/kyua/doc/manbuild.sh  -v "CONFDIR=/etc/kyua"  -v "DOCDIR=/nonexistant"  -v "EGDIR=/usr/share/examples/kyua"  -v "MISCDIR=/usr/share/kyua/misc"  -v "PACKAGE=kyua"  -v "STOREDIR=/usr/share/kyua/store"  -v "TESTSDIR=/usr/tests"  -v "VERSION=0.13"  /usr/src/contrib/kyua/doc/kyua-about.1.in kyua-about.1
	/bin/sh: /usr/src/contrib/kyua/doc/manbuild.sh: Permission denied
	*** Error code 126

l  /usr/src/contrib/kyua/doc/manbuild.sh
	-rw-r--r--  1 jhs  staff  5187 Mar 25 12:34 /usr/src/contrib/kyua/doc/manbuild.sh

chmod a+x /usr/src/contrib/kyua/doc/manbuild.sh

make	# succeeds but wrong solution

chmod a-x /usr/src/contrib/kyua/doc/manbuild.sh
cd /usr/src/usr.bin/kyua ;  make clean
source `which unsetenv.csh`
# SH is not set
make clean ; make
/bin/sh: /usr/src/contrib/kyua/doc/manbuild.sh: Permission denied

*** src/usr.bin/kyua/Makefile.orig	Wed Mar 25 12:34:45 2020
--- src/usr.bin/kyua/Makefile	Sat Mar 28 01:38:21 2020
***************
*** 49,55 ****
  .PATH: ${KYUA_SRCDIR}/doc
  .for man in ${MAN}
  ${man}: ${man}.in
! 	${SH} ${KYUA_SRCDIR}/doc/manbuild.sh \
  	    -v "CONFDIR=${KYUA_CONFDIR}" \
  	    -v "DOCDIR=${KYUA_DOCDIR}" \
  	    -v "EGDIR=${KYUA_EGDIR}" \
--- 49,55 ----
  .PATH: ${KYUA_SRCDIR}/doc
  .for man in ${MAN}
  ${man}: ${man}.in
! 	/bin/sh ${KYUA_SRCDIR}/doc/manbuild.sh \
  	    -v "CONFDIR=${KYUA_CONFDIR}" \
  	    -v "DOCDIR=${KYUA_DOCDIR}" \
  	    -v "EGDIR=${KYUA_EGDIR}" \

The diff above works, but is not sophisticated enough to represent what 
someone is trying to do with SH ?

Cheers
--
Julian Stacey, Consultant Systems Engineer, BSD Linux http://berklix.com/jhs/
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