[exim] Corrupted log lines when validating DKIM signatures

Hi,

I'm sometimes seeing some corrupted output in my Exim logs when verifying
DKIM signatures, for example:

2018-08-21 11:56:58 1fs4LJ-0001VN-G3 DKIM: d=email.tladoonline.com
s=10dkim1 c=relaxed/relaxed a=rsa-sha256 b=2048
i=+Ud^A^D<A8><EF><CE><DE><F9><E0><DC>V?<A4><9E><DD> W

Sometimes I get something more valid like this:

2018-08-22 09:05:09 1fsO8a-0005D2-VN DKIM: d=advice.hmrc.gov.uk s=15q1
c=relaxed/relaxed a=rsa-sha1 b=2048 i=@advice.hmrc.gov.uk [verification
succeeded]

This is on Exim 4.89 in Debian 9.5. Is this a known, fixed issue?

regards,
John