[Exim] lowercased $local_part

Hi!

I see that $local_part passed to a pipe transport is lowercased.
I want caseless conditions but preserve case on commands arguments.
I've specify caseful_local_part for the router, but it makes
caseful conditions. Documentation says that by default conditions
are caseless but case is preserved. Is it documentation mistake or
my misunderstanding?

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                                Lucky carrier,
                                                  Паша.