Check for existing factory in registered_sources
Check for existing factory in registered_sources

check for existing factory with that name before appending
in registered_sources

https://bugzilla.gnome.org/show_bug.cgi?id=765032

GNOME/libchamplain,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,GNOME/libchamplain