Tabulation in multiline headers

[Sergei Shilovsky]

Lets consider this message:

    id:87r5aucoeg.fsf at servo.finestructure.net

Its subject spreads over 2 lines and the 2nd line is indented with
<Tab> in the file:

    Subject: running the crypto branch [was: Re: Hiding HTML mime-parts and/or
    <Tab--->scrubbing (gmail's) HTML-based citation]

The issue is that notmuch_message_get_header() returns this whole line
with the Tab
character (though I guess it should not):

    running the crypto branch [was: Re: Hiding HTML mime-parts
and/or<Tab>scrubbing (gmail's) HTML-based citation]

This file could be imported from gmane though with mb2md. My test long
subject message (sent via gmail) didn't got any tabulation.

 No idea where this tabulation could came from, but would that be
correct to replace <tab> with space in libnotmuch itself?

-- 
С уважением,
Сергей Шиловский
Sergei Shilovsky