Doesn't work with Debian 11

[jeroenjacobs79]

Build fails with following error:

make builddeb NO_SIGN=1
make debianize
make[1]: Entering directory '/home/box-admin/yubikey-luks'
rm -fr DEBUILD
mkdir -p DEBUILD/yubikey-luks-0.5.1
cp -r *  DEBUILD/yubikey-luks-0.5.1 || true
cp: cannot copy a directory, 'DEBUILD', into itself, 'DEBUILD/yubikey-luks-0.5.1/DEBUILD'
(cd DEBUILD; tar -zcf yubikey-luks_0.5.1.orig.tar.gz --exclude=yubikey-luks-0.5.1/debian  yubikey-luks-0.5.1)
make[1]: Leaving directory '/home/box-admin/yubikey-luks'
(cd DEBUILD/yubikey-luks-0.5.1; debuild -uc -us)
/bin/sh: 1: debuild: not found
make: *** [Makefile:18: builddeb] Error 127

[jeroenjacobs79]

Something like this works from the shell:
cp -r !(DEBUILD) DEBUILD/yubikey-luks-0.5.1 || true

However, it doesn't work when I change the Makefile. I tried this:

debianize:
        rm -fr DEBUILD
        mkdir -p DEBUILD/${SRC_DIR}
        cp -r  !(DEBUILD) DEBUILD/${SRC_DIR} || true
        (cd DEBUILD; tar -zcf yubikey-luks_${VERSION}.orig.tar.gz --exclude=${SRC_DIR}/debian  ${SRC_DIR})

But this results in an error:

make builddeb NO_SIGN=1
make debianize
make[1]: Entering directory '/home/box-admin/yubikey-luks'
rm -fr DEBUILD
mkdir -p DEBUILD/yubikey-luks-0.5.1
cp -r  !(DEBUILD) DEBUILD/yubikey-luks-0.5.1 || true
/bin/sh: 1: Syntax error: "(" unexpected
make[1]: *** [Makefile:13: debianize] Error 2
make[1]: Leaving directory '/home/box-admin/yubikey-luks'
make: *** [Makefile:17: builddeb] Error 2