Out-of-tree build of zsh 5.7.1 fails in install.man

[Michal Nowak <mnowak@xxxxxxxxxxxxx>]

Hello,

zsh 5.7.1 build fails on OpenIndiana (illumos kernel) with:

for file in zsh.1 zshbuiltins.1 zshcalsys.1 zshcompctl.1 zshcompwid.1 
zshcompsys.1 zshcontrib.1 zshexpn.1 zshmisc.1 zshmodules.1 zshoptions.1 
zshparam.1 zshroadmap.1 zshtcpsys.1 zshzftpsys.1 zshzle.1 zshall.1; do \
    test -s $file || exit 1; \
    /usr/bin/ginstall -c -m 644 $file 
/export/home/newman/ws/oi-userland/components/shell/zsh/build/prototype/i386/usr/share/man/man1/`echo 
$file | sed 's|zsh|zsh|'` || exit 1; \
done
make[2]: *** [Makefile:474: install.man] Error 1
make[2]: Leaving directory 
'/export/home/newman/ws/oi-userland/components/shell/zsh/build/amd64/Doc'
make[1]: *** [Makefile:222: install.man] Error 2
make[1]: Leaving directory 
'/export/home/newman/ws/oi-userland/components/shell/zsh/build/amd64'

File 'zsh.1' et al. is not in 
'/export/home/newman/ws/oi-userland/components/shell/zsh/build/amd64/Doc', 
I can see them in the sources at: 
'/export/home/newman/ws/oi-userland/components/shell/zsh/zsh-5.7.1/Doc'.

I perform out-of-tree build from 
'/export/home/newman/ws/oi-userland/components/shell/zsh/build/amd64', 
sources are at 
'/export/home/newman/ws/oi-userland/components/shell/zsh/zsh-5.7.1/'.

Build used to work with 5.6.2.

If I revert change "43692: Generate man pages in the build dir, rather 
than the source dir" 
(https://sourceforge.net/p/zsh/code/ci/76a16498d5c76aa3fee0805b8241263249d71b94/), 
build works again.

Our build system is at 
https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/components/shell/zsh/ 
(in case we messed-up something).

Thanks,
Michal