Some days ago it worked (grabbed some random Travis check: https://travis-ci.org/geany/geany/jobs/414064315#L934). Hopefully it will come back soon. If not, we still have a copy on the server where the nightlies are built.
IIRC we thought about hosting the bundle ourselves on download.geany.org but I don't remember why we didn't do it so far. Maybe licensing issues.
Anyway, it's not totally critical I'd say as this is currently only used for Travis CI builds and only for the GTK3-Windows combination.