icinga2/icingaweb2: Update get_snapshot to dump branch into version file

get_snapshot

@@ -66,4 +66,4 @@ gzip -vf9 "${tarball}"
 sha256sum "${tarball}.gz"
 
 # store package version for build scripts
-echo -e "${package_version}\t$(git rev-parse HEAD)\t$(basename "${tarball}.gz")" > "${workdir}/${PROJECT}.version"
+echo -e "${package_version}\t$(git rev-parse HEAD)\t$(basename "${tarball}.gz")\t${UPSTREAM_GIT_BRANCH}" > "${workdir}/${PROJECT}.version"