[sources] Check source's url attribute value on creation/modification Similarly as for config. Now, ldap source validation is properly done there instead of at initialization time.

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
https://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))