There was discussion about this on ubuntu-devel several years ago: https://lists.ubuntu.com/archives/ubuntu-devel/2007-March/023332.html
I don't know that it was ever codified in policy, but the Vcs-* fields aren't codified in Debian Policy either (they're part of the Developer's Reference: http://www.debian.org/doc/manuals/developers-reference/best-pkging-practices.html#bpp-vcs)
There was discussion about this on ubuntu-devel several years ago: https:/ /lists. ubuntu. com/archives/ ubuntu- devel/2007- March/023332. html
I don't know that it was ever codified in policy, but the Vcs-* fields aren't codified in Debian Policy either (they're part of the Developer's Reference: http:// www.debian. org/doc/ manuals/ developers- reference/ best-pkging- practices. html#bpp- vcs)