[req.find] Use vreg.schema.eschema for eschema lookup If an etype is non-existant, using vreg.schema[etype] raises a confusing error complaining about a non-existing relation. This is because of the implementation of vreg.schema.__getitem__ that look first in entities and then in relations. Using directly vreg.schema.eschema restrict the lookup to etypes only, hence raises a meaningful error when the etype does not exist.

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')