Order by with column ordinal and collate - fails to parse

Hi all,

I seem to be having problems constructing a query that combines the use of
distinct, order by, and collate key words.

For instance:

# select distinct(value) from properties order by 1 collate "C";
ERROR: collations are not supported by type integer
LINE 1: ... distinct(value) from properties order by 1 collate "C...
^
# select distinct(value) from properties order by distinct(value) collate
"C";
ERROR: syntax error at or near "distinct"
LINE 1: ...ct distinct(value) from properties order by distinct(v...
^
# select distinct(value) as foo from properties order by foo collate "C";
ERROR: column "foo" does not exist
LINE 1: ...tinct(value) as foo from properties order by foo collat...

Am I just being a numpty here? I can work around it with a subquery, but
this seems like a bug to me. Particularly the first example where my
ordinal field reference is treated as an integer literal. I should note
that the field 'value' is of type 'text' (not integer).

Any input appreciated. Thanks :)