Test suite fails on IPv6-only hosts

Currently, microhttpd (MHD) is setup with IPv4 sockets. This test suite setup fails on IPv6-only hosts as recently observed on some Debian build servers (cf. amd64 build log), e.g.:

29.164346.060 dequeue job http://localhost:42485/index.html
29.164346.060 resolving localhost:42485...
29.164346.060 has ::1:42485
29.164346.060 has ::1:42485
29.164346.060 has ::1:42485
29.164346.060 trying ::1:42485...
29.164346.061 established connection localhost
Failed to send 215 bytes (hostname='localhost', ip=::1, errno=111)
29.164346.061 host_increase_failure: localhost failures=1
29.164346.061 host_increase_failure: qsize=0
29.164346.061 [0] action=3 pending=1 host=0x557dfe864360
29.164346.061 closing connection
29.164346.061 released job http://localhost:42485/index.html
29.164346.061 [0] action=1 pending=0 host=0x0
29.164346.061 host localhost is blocked (qsize=1)

Is there a reason to not setup MHD with dual-stack sockets to support building wget2 on IPv6-only hosts as well? If that is not possible, would it be possible to add a new option to configure for MHD to use IPv6 sockets instead of IPv4 sockets (like --enable-ipv6-testing for instance)?