[rql2sql] fix bad sql generated when outer joining 'identity' relation and lhs var comes from a subquery. Closes #3099418
The generated SQL was attempting to access table.cw_eid which doesn't exist.
[system]
db-driver = postgres
db-host = localhost
db-port = 5433
adapter = native
db-name = cw_fti_test
db-encoding = UTF-8
db-user = syt
db-password = syt
[admin]
login = admin
password = gingkow