BUG #6152: possibly wrong display of pg_settings.enumvals for default_transaction_isolation

The following bug has been logged online:

Bug reference: 6152
Logged by: Christoph Anton Mitterer
Email address: calestyo(at)scientia(dot)net
PostgreSQL version: 9.0
Operating system: Debian sid
Description: possibly wrong display of pg_settings.enumvals for
default_transaction_isolation
Details:

Hi

$ psql -c 'SELECT name,vartype,enumvals FROM pg_settings;' | grep
default_transaction_isolation
could not change directory to "/root"
default_transaction_isolation | enum | {serializable,"repeatable
read","read committed","read uncommitted"}

Using e.g.:
default_transaction_isolation = "read committed"
does not work however. It only works in single quotes.

If I don't get something wrong, there should be either a bug in the output
of pg_settings.enumvals or the parsing of the config file.

Cheers,
Chris.