Wrong Assert in PageIndexMultiDelete?

Hi, hackers!

I am trying to create new index access method.
And I found strange Assert in PageIndexMultiDelete
<http://doxygen.postgresql.org/bufpage_8c_source.html#l00791> function.

Assert
<http://doxygen.postgresql.org/c_8h.html#a706ac5b1a53bd04067f81924b92cb9f6>(nitems
< MaxIndexTuplesPerPage
<http://doxygen.postgresql.org/itup_8h.html#adb7c94e95ce112eb47d71f7797604ddb>
);

Is '<' sign is correct? I thougt it should be '<='.
Is it a bug or just my misunderstanding?

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Best regards,
Lubennikova Anastasia