Template support doesn't work with resource overlays
The new GTK+ template support does this when handling templates with resource paths:
Gio.resources_get_info( self.resource_path, Gio.ResourceLookupFlags.NONE)
which I think is there to give the user a much nicer error message when the template is missing. However, this means that it's not possible to use the template API together with resource overlays specified by
G_RESOURCE_OVERLAYS, because of glib#1445 (closed).
Given that pygobject isn't actually using anything it gets from the
Gio.resources_get_info() call... would it be possible to use something else to detect whether the user has provided a bad template?