Why am I getting the error "WARNING server login failed..." when using PGBouncer on Heroku Postgres

Issue

When trying to connect to Heroku Postgres with a custom PGBouncer installation, all connections fail with an error like

WARNING server login failed: FATAL password authentication failed for user "..."

Note that this does not apply when using the Heroku PGBouncer buildpack.

Resolution

Any of the above should work around the issue