psql --command option ignores --variable's

Hi all,

It seems the behaviour of the ‹command / -c option is such that it will
ignore any variables set on the command-line.

:~ psql --variable TESTVAR='123' --command 'select :TESTVAR;'
ERROR: syntax error at or near ":"
LINE 1: select :TESTVAR;
^

:~$ psql --variable TESTVAR='123'
psql (9.1.9)
Type "help" for help.

timk=> select :TESTVAR;
?column?
----------
123
(1 row)

Obviously, there are ways around this, but is this expected behaviour?

Tim