perl-Dancer has an optional test dependency of perl(Dancer::Session::Cookie) >= 0.14, which pulls in perl-Dancer-Session-Cookie. However, that requires perl-Dancer itself and thus introduces a circular dependency. Suggested fix - wrap that buildreq with a %perl_bootstrap conditional:

diff --git a/perl-Dancer.spec b/perl-Dancer.spec
index c7ee3be..04084a9 100644
--- a/perl-Dancer.spec
+++ b/perl-Dancer.spec
@@ -62,7 +62,10 @@ BuildRequires:  perl(Test::Builder)
 BuildRequires:  perl(URI::Escape)
 # Optional tests:
 BuildRequires:  perl(HTTP::Parser::XS)
+# Dancer::Session::Cookie needs Dancer itself
+%if 0%{!?perl_bootstrap:1}
 BuildRequires:  perl(Dancer::Session::Cookie) >= 0.14
+%endif
 Requires:       perl(:MODULE_COMPAT_%(eval "`perl -V:version`"; echo $version))
 Requires:       perl(HTTP::Body) >= 1.07
 Requires:       perl(HTTP::Server::Simple::PSGI) >= 0.11

I tested this on F-17 as mod_perl is pulled in as a buildreq and it's currently uninstallable in Rawhide.