Some .dsc files have a Vcs-Git field, next to Vcs-Browser. From zsh_5.2-3.dsc:

Vcs-Browser: https://anonscm.debian.org/cgit/collab-maint/zsh.git
Vcs-Git: git://anonscm.debian.org/collab-maint/zsh.git -b debian

Although these are somewhat processed by and stored as vcs-url it might be worth breaking it down a bit more (the type of vcs, and so on). Also, as the repositories mentioned in Vcs-Git field are where the Debian specific metadata lives (such as the .dsc itself) it might be worth treating it differently (and potentially use it to mine even more information).