[multi-sources] closes #1918120: drop behaviour leading to wrong result as demonstrated by the ticket The formerly implemented behaviour doesn't seems to be useful, nor to have a chance to be correct. At least no test case demonstrate the opposite, so I've dropped it.

# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s specific hooks and operations"""