cubicweb #3099418 bad sql generated in case of outer joined 'X identity Y' with X coming from a subquery [validation pending]

prioritynormal
typebug
done in3.17.7
load0.200
load left0.000
closed by#a68b2fe8a800 [rql2sql] fix bad sql generated when outer joining 'identity' relation and lhs var comes from a subquery. Closes #3099418
patch[rql2sql] fix bad sql generated when outer joining 'identity' relation and lhs var comes from a subquery. Closes #3099418 [applied]