The following bug has been logged on the website:
Bug reference: 14912
Logged by: Mark Wood
Email address: mhwood@ameritech.net
PostgreSQL version: 9.6.6
Operating system: Gentoo Linux, kernel 4.12, glibc 2.25-r9
Description:
The 'psql' man page explains that the default database name is your OS
username, and that $PGDATABASE can be used to supply a different default.
That is true *unless* using -l / --list. The code shows that this option
defaults to 'postgresql' instead, overriding the libpq defaulting. I spent
quite some time reading and experimenting to determine why I was not seeing
the documented behavior.
The actual behavior may be reasonable, but if so it should be documented as
an exception for the --list function.