PGPASSFILE not getting passed to sql-dump

[kalpaitch]

I am running drush sql-dump on a postgres 9.5 instance, and it's still asking for a password prompt.

Running: drush @xxxxx.xxxxx sql-dump --result-file='/tmp/db-dump-test-unsanitized.sql' --extra='-O -x' --verbose
Loaded alias @xxxxx.xxxxx from file /var/www/xxxxx/web/sites/all/drush/xxxxx.aliases.drushrc.php    [notice]
Executing: PGPASSFILE=/tmp/drush_bZy0Wm psql -q --dbname=par --host=localhost --port=5432 --username=xxxxx  --no-align --field-separator="	" --pset tuples_only=on --file /tmp/drush_2z1SbB
Calling system((pg_dump  par --host=localhost --port=5432 --username=par -O -x --clean && pg_dump --schema-only --table=flood --table=sessions --table=watchdog xxxx --host=localhost --port=5432 --username=xxxxx -O -x --clean) > /tmp/db-dump-test-unsanitized.sql);
Password: 

I was expecting drupal to pass the pwd to postgres by writing a temporary PGPASSFILE, which it seems to do for the psql command, but perhaps it's not passing that along to the pg_dump command??

System Configuration

Drush 8.18
Drupal 8.6
PHP 7.1

[weitzman]

Fixed in Drush 9.6

[kalpaitch]

See #3330 (comment) parent issue requires further work

[jcnventura]

This needs a backport to Drush 8, please.