so that build will not fail if the directory was left during previous
builds.

This updates links to slapos.git in the tree to point to new location.

We do so whole-tree except one place in stack/monitor/ :

    [download-monitor-static]
    recipe = hexagonit.recipe.download
    url = http://git.erp5.org/gitweb/slapos.git/snapshot/930be99041ea26b7b1186830e5eb56ef0acc1bdf.tar.gz
    ...

(see d8800c0b "monitor: Download statics files from snapshot")

The reason we do not update that link yet, is that 930be99041ea26b7b1186830e5eb56ef0acc1bdf
is a tree object and gitlab does not allow to dowload tree object as archives (yet ?)

So for now that link stays unconverted - and we'll think how to do with it.