closes #601987
1) sqlutils.restore_from_file have to use its confirm argument when
a command fail, to propose to continue there (this can't be handled
by the caller)
2) source.restore method hence needs to take this confirmation callback
as argument
3) properly fix places where 'drop' was given instead of 'confirm'
add_relation_type('prefered_form')
rql('SET X prefered_form Y WHERE Y canonical TRUE, X identical_to Y')
checkpoint()
drop_attribute('EmailAddress', 'canonical')
drop_relation_definition('EmailAddress', 'identical_to', 'EmailAddress')
if 'see_also' in schema:
sync_schema_props_perms('see_also', syncprops=False, syncrdefs=False)