[multi-sources-removal] drop source location search on glob_*[entity|relation] methods source is now always the system source Related to #2919300 [jcr: fix wrong rebase in symmetric relation removal]

from os.path import join
assert __file__.endswith(join('scripts', 'script1.py')), __file__
assert '__main__' == __name__, __name__
assert [] == __args__, __args__