This can cause problems with halfway downloaded files. In the future it
would be better to save partially downloaded data into a .part file and
the continue that even with GIS_ONCE.
gchar *uri = _make_uri(self, tile);
gchar *tilep = gis_tile_get_path(tile);
gchar *local = g_strdup_printf("%s%s", tilep, self->extension);
gchar *uri = _make_uri(self, tile);
gchar *tilep = gis_tile_get_path(tile);
gchar *local = g_strdup_printf("%s%s", tilep, self->extension);
gchar *path = gis_http_fetch(self->http, uri, local,
mode, callback, user_data);
g_free(uri);
gchar *path = gis_http_fetch(self->http, uri, local,
mode, callback, user_data);
g_free(uri);