phase2: fix obsolete assumption about feed methods

phase2: fix obsolete assumption about feed methods

In commit 7fae1e5677e9 ("feeds: use git-src-full to allow Git
versioning") there was `src-git` method of shallow clone replaced with
`src-git-full` and this has caused issue with GitPoller configuration as
it only assumed, that only `src-git` method is going to be used for feed
updates. Fix currently stuck buildbot master by allowing usage of both
Git update methods.

Signed-off-by: Petr Štetiar <ynezz@true.cz>