ssvnc: Fails to build source after successful build

his package fails to build a source package after a successful build
(dpkg-buildpackage ; dpkg-buildpackage -S).

This is probably a clear violation of Debian Policy section 4.9 (clean target),
but this is filed as severity:minor for now, because a discussion on
debian-devel showed that we might want to revisit the requirement of a working
'clean' target.

More information about this class of issues, included common problems and
solutions, is available at
https://wiki.debian.org/qa.debian.org/FTBFS/SourceAfterBuild

Relevant part of the build log:
> cd /<<PKGBUILDDIR>> && runuser -u user42 -- dpkg-buildpackage --sanitize-env -us -uc -rfakeroot -S
> ------------------------------------------------------------------------------------------------------------------
>
> dpkg-buildpackage: info: source package ssvnc
> dpkg-buildpackage: info: source version 1.0.29-6
> dpkg-buildpackage: info: source distribution unstable
> dpkg-buildpackage: info: source changed by Magnus Holmgren <email address hidden>
> dpkg-source --before-build .
> fakeroot debian/rules clean
> dh_testdir
> dh_testroot
> rm -f build-stamp configure-stamp
> /usr/bin/make clean
> make[1]: Entering directory '/<<PKGBUILDDIR>>'
> cd vnc_unixsrc/libvncauth; /usr/bin/make clean
> make[2]: Entering directory '/<<PKGBUILDDIR>>/vnc_unixsrc/libvncauth'
> rm -f libvncauth.a vncauth.o d3des.o
> make[2]: Leaving directory '/<<PKGBUILDDIR>>/vnc_unixsrc/libvncauth'
> cd vnc_unixsrc/vncviewer; /usr/bin/make clean
> make[2]: Entering directory '/<<PKGBUILDDIR>>/vnc_unixsrc/vncviewer'
> rm -f vncviewer argsresources.o caps.o colour.o cursor.o desktop.o dialogs.o fullscreen.o listen.o misc.o popup.o rfbproto.o selection.o shm.o sockets.o tunnel.o vncviewer.o
> make[2]: Leaving directory '/<<PKGBUILDDIR>>/vnc_unixsrc/vncviewer'
> if [ "Xultraftp" != "X" ]; then cd ultraftp; /usr/bin/make clean; fi
> make[2]: Entering directory '/<<PKGBUILDDIR>>/ultraftp'
> rm -f *.class *.jar
> make[2]: Leaving directory '/<<PKGBUILDDIR>>/ultraftp'
> cd vncstorepw; /usr/bin/make clean
> make[2]: Entering directory '/<<PKGBUILDDIR>>/vncstorepw'
> rm -f *.o vncstorepw unwrap.so lim_accept.so ultravnc_dsm_helper
> make[2]: Leaving directory '/<<PKGBUILDDIR>>/vncstorepw'
> make[1]: Leaving directory '/<<PKGBUILDDIR>>'
> rm vnc_unixsrc/*/Makefile
> rm: cannot remove 'vnc_unixsrc/*/Makefile': No such file or directory
> make: *** [debian/rules:41: clean] Error 1
> dpkg-buildpackage: error: fakeroot debian/rules clean subprocess returned exit status 2
>
> E: Command 'cd /<<PKGBUILDDIR>> && runuser -u user42 -- dpkg-buildpackage --sanitize-env -us -uc -rfakeroot -S' failed to run.

The full build log is available from:
http://qa-logs.debian.net/2023/08/13/ssvnc_1.0.29-6_unstable.log

If you reassign this bug to another package, please mark it as 'affects'-ing
this package. See https://www.debian.org/Bugs/server-control#affects

If you fail to reproduce this, please provide a build log and diff it with mine
so that we can identify if something relevant changed in the meantime.