I think the bug is in perl-XML-SAX - it specifies both build and install time dependencies to some XML-LibXML modules, but the specfile doesn't mention why, and grepping for libxml (case insensitively) through XML-SAX sources hits just some documentation.

I found XML::LibXML only in this comment:
<cite>Note that you should check the output of this - \$(NAME) will use the name of your distribution, which may not be exactly what you want. For example XML::LibXML has a driver called XML::LibXML::SAX::Generator, which is used in place of \$(NAME) in the above.<\cite>

It's true that XML::LibMXL is set in ParserDetails.ini for use. But I suppose we can build without it.

There is still a problem here. perl-XML-SAX has explicit runtime dependencies on perl(XML::LibXML) and perl(XML::LibXML::Common), and perl-XML-LibXML has a build requirement of perl(XML::SAX), so tries to pull itself into its own build.

I don't understand why there are still these explicit runtime dependencies on perl(XML::LibXML) and perl(XML::LibXML::Common) in perl-XML-SAX. Getting rid of them would fix this loop.

perl-XML-LibXML really does use XML::SAX so that's a real dependency.

Also the %triggerun script for perl-XML-LibXML < 1.58-8 can probably go as that version of perl-XML-LibXML dates back to 2006.

I guess I did what you are saying. I removed perl(XML::LibXML) and perl(XML::LibXML::Common) from BR and left them in Requires for perl-XML-LibXML.

I'm afraid to touch triggers there. I spent long time to fix those two packages in RHEL.

If you see something what I missed, please remove/fix it.

I see that perl-XML-LibXML-1.58-6 (i.e. < 1.58-8) is still in EL-5 so I guess there's some justification for the trigger still.

I've removed the runtime Requires for perl(XML::LibXML) and perl(XML::LibXML::Common) that you left in as nobody can see why they're needed and they are the cause of the circular build dep. If anyone can see why a runtime dependency should still be needed, please say.

The new build is: perl-XML-SAX-0.99-3.fc18