Also note that because of the package being out of date, and no response from maintainer yet, downstream in Ubuntu the packages have diverged so that this can be updated downstream from Debian. This is visible at https://launchpad.net/ubuntu/+source/xca/2.1.2-0ubuntu1 if you wish to see the package properly.
NOTE: there is no 'source' package Vcs store anymore that can be publicly used, so this package drops the Vcs-Git line in control. Eventually I'd like to include this in Salsa, but that's not yet doable. Thomas