Deb: test-deb supports build tag Debian revision

Packages build with a build tag as `build-deb ubuntu bionic +tag` will
have "+tag" in Debian package name as Debian revision. test-deb now will
use the package with the tag for testing purposes.

builder/test-deb

@@ -7,6 +7,7 @@ cd "$(dirname "$0")"
 
 tester_image=kasmvnctester_${os}:$os_codename${build_tag_for_images}
 docker build --build-arg KASMVNC_PACKAGE_DIR="build/${os_codename}" \
+  --build-arg BUILD_DEBIAN_REVISION="$build_debian_revision" \
   -t "$tester_image" \
   -f dockerfile.${os}_${os_codename}${build_tag}.deb.test .
 docker run -it -p 443:8443 --rm \