FTS Solr errors using doveadm

[Stuart Henderson]

On 2018-06-07, Ricardo Branco <ricardo.branco at wenn.com> wrote:
> Solr 7 returns JSON by default but fts_solr requires XML.
>
> Would be good to have wt=xml added to the query to force it to xml all the time, this would prevent errors if solr has 
> not had xml set as default for index.

This is already done in Dovecot 2.3.x, the same patch works in 2.2.x.

https://github.com/dovecot/core/commit/f987ef0632fc.patch