Another question:
If I do not use on gloox::DiscoNodeHandler and 
gloox::AdhocCommandProvider, then why can not I get the appropriate 
STANZA through gloox :: IqHandler?
I'm comfortable in my program to respond to the request asynchronously.

my code:
myClient->disco()->registerNodeHandler(rootDiscoHandler_, "");

I send:

<iq type="get" to="xxxxx" id="ac4da">
<query xmlns="http://jabber.org/protocol/disco#info"/>
</iq>


<iq type="get" to="xxxxx" id="ac4ea">
<query xmlns="http://jabber.org/protocol/disco#items"/>
</iq>

I received:

<iq from="xxxxx" type="result" xml:lang="en" to="liuch@jabber.ru/rs04" 
id="yyyyy">
<query xmlns="http://jabber.org/protocol/disco#info">
<identity category="client" type="bot"/>
<feature var="http://jabber.org/protocol/commands"/>
<feature var="http://jabber.org/protocol/disco#info"/>
<feature var="http://jabber.org/protocol/disco#items"/>
<feature var="jabber:iq:version"/>
<feature var="urn:xmpp:ping"/>
<feature var="vcard-temp"/>
</query>
</iq>

<iq from="xxxxx" type="result" xml:lang="en" to="yyyyy" id="ac4ea">
<query xmlns="http://jabber.org/protocol/disco#items">
<item node="http://jabber.org/protocol/commands" name="Ad-Hoc 
Commands" jid="zzzzz"/>
</query>
</iq>

Was called by only handleDiscoNodeItems. My handler was returned to an 
empty list, but as you can see, STANZA it is not.

p.s. Sorry for my english :)

Cursorily looked at the patch, but now I see that the patch only 
applies to ExtDiscoItems, but does not correct the situation with 
ExtDiscoInfo. Am I right?

Later I'll check the patch.

Thank you.

Thanks for the report.
Could you please check if the attached patch solves the problem?

A quote from the documentation:
...
But really can not get a request to the root element.
I looked method bool Disco::handleIq( const IQ& iq )
In the case of an empty node works the other piece of code.

I look forward to answering.