Please backport the upstream commit "gdbus: don't warn when returning a value on a closed connection" https://git.gnome.org/browse/glib/commit/?id=c6862451411ae3039029fdd1e3697343fa2aed19 (from https://bugzilla.gnome.org/show_bug.cgi?id=753839) We hit this warning while testing NetworkManager. As we test with G_DEBUG=fatal-warnings, this is bad for testing (bug 1253318)
btw, due to the rebase to 2.50.3, this automatically is fixed in rhel-7.4.
*** This bug has been marked as a duplicate of bug 1266470 ***