oca_dependencies.txt ignored if FETCH_OCA_DEPENDENCIES=False

[seb-elico]

When cloning multiple independent GH repos (see https://github.com/Elico-Corp/odoo-docker#fetch_multiple_repos), in case ENV var FETCH_OCA_DEPENDENCIES=False is used, the addons path will be the Odoo default one (i.e. it doesn't include the repos listed in oca_dependencies.txt as well as their child repos).

To be noted that if there's only 1 master repo cloned (i.e. using ENV var ADDONS_REPO), there's no such bug.