Comment 2 for bug 42869

In the description above, I forgot to mention that the following file was also updated:

/usr/share/mime/packages/seahorse.xml

The "application/pgp-encrypted" section now looks like this:
-----------------------------------------------------------------------------------
  <mime-type type="application/pgp-encrypted">
    <magic priority="90">
      <match type="string" value="-----BEGIN PGP MESSAGE-----" offset="0"/>
    </magic>
    <glob pattern="*.pgp"/>
    <glob pattern="*.gpg"/>
    <glob pattern="*.asc"/>
  </mime-type>
-----------------------------------------------------------------------------------
Please note, this had still not fixed the problem for me.