except all & WITH - syntax error?

Hi!
Something strange happened to me right now. I'm trying to compare results
from one query with rewritten version and everything is ok with this order:

WITH abc AS (SELECT 1) SELECT 1
except all
SELECT 1

but when I'm trying other way around it throws an error:
SELECT 1
except all
WITH abc AS (SELECT 1) SELECT 1

ERROR: syntax error at or near "WITH" LINE 3: WITH abc AS (SELECT 1) SELECT
1 ^ SQL state: 42601 Character: 21

"PostgreSQL 9.6.9 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5
20150623 (Red Hat 4.8.5-16), 64-bit"

Is this expected behaviour?
It's much harder to optimize queries without this option.

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