Hello Raphaël Halimi. Thanks for your bug report and patch!
I'd like to question a conflict I see in the reasoning around "Forwarded: not-needed". Why should this not be forwarded upstream? What harm would this change do upstream? If it's not suitable for upstream, why would it be suitable for debian? glib is a critical component which atleast me (which is not the one deciding this) would like to avoid patching at all. In general I also think that adding patches which will have to be carried *forever* is something you never want to add (unless absolutely necessary). I think it's important to atleast have answers to these questions on the record for the future.... Regards, Andreas Henriksson