As reported downstream at:
http://bugs.gentoo.org/show_bug.cgi?id=349236

Some glib tests need dbus-python:
PASS: socket
TEST: gdbus-connection... (pid=18254)
  /gdbus/connection/basic:                                             OK
  /gdbus/connection/life-cycle:                                        OK
  /gdbus/connection/send:                                              OK
  /gdbus/connection/signals:                                           OK
  /gdbus/connection/filter:                                           
Traceback (most recent call last):

+ Trace 225828

Timeout waiting 30 sec on service
**
ERROR:gdbus-connection.c:826:test_connection_filter_on_timeout: code should not
be reached
cleaning up bus with pid 18284
FAIL
GTester: last random seed: R02S5afcea46d559ab3f2f36c546047ab7e0
/bin/sh: line 1: 16677 Terminated              MALLOC_CHECK_=2
MALLOC_PERTURB_=$((${RANDOM:-256} % 256)) ../../glib/gtester --verbose
memory-input-stream memory-output-stream readwrite g-file g-file-info
converter-stream data-input-stream data-output-stream g-icon
buffered-input-stream buffered-output-stream sleepy-stream filter-streams
volumemonitor simple-async-result srvtarget contexts gsettings gschema-compile
async-close-output-stream gdbus-addresses network-address gdbus-message socket
gdbus-connection gdbus-connection-slow gdbus-names gdbus-proxy
gdbus-proxy-well-known-name gdbus-introspection gdbus-threading gdbus-export
gdbus-error gdbus-peer gdbus-exit-on-close gdbus-non-socket gdbus-bz627724
appinfo contenttype file live-g-file desktop-app-info unix-fd unix-streams
gdbus-serialization
make[4]: *** [test-nonrecursive] Error 143
make[4]: Leaving directory
`/var/tmp/portage/dev-libs/glib-2.26.1/work/glib-2.26.1/gio/tests'
make[3]: *** [check-am] Error 2
make[3]: Leaving directory
`/var/tmp/portage/dev-libs/glib-2.26.1/work/glib-2.26.1/gio/tests'
make[2]: *** [check-recursive] Error 1
make[2]: Leaving directory
`/var/tmp/portage/dev-libs/glib-2.26.1/work/glib-2.26.1/gio'
make[1]: *** [check] Error 2
make[1]: Leaving directory
`/var/tmp/portage/dev-libs/glib-2.26.1/work/glib-2.26.1/gio'
make: *** [check-recursive] Error 1

But this is a bit problematic because depending on dbus-python would add a dependency on dbus-glib, that depends on glib => Circular deps problem

I would suggest that glib tests needing dbus-python would not die if dbus-python is not present, being them skipped in that case and only run with dbus-python is installed.

What do you think?

Thanks a lot