Index usage for BYTEA column in OR/IN clause

Is it true that the planner currently doesn't utilize index for BYTEA
column in OR or IN clause?

  -- b is an indexed BYTEA column

  explain select * from t where b='foo';                    -- index scan
  explain select * from t where b like 'f%';                -- index

  explain select * from t where b='foo' or b='bar';         -- seq scan
  explain select * from t where b='foo' or b like 'b%';     -- seq
  explain select * from t where b like 'f%' or b like 'b%'; -- seq
  explain select * from t where b in ('foo','bar');         -- seq

Currently I'm setting enable_seqscan to off for these...

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dave