Restore GPL prefix

src/copcat.cpp

@@ -8,8 +8,9 @@ const MString CopernicusCatalog::caturl = "https://stac.marine.copernicus.eu/met
 CopernicusCatalog::CopernicusCatalog()
 {
  // Cache
- michlib::GPL.UsePrefix("COPERNICUS");
+ auto oldprefix = michlib::GPL.UsePrefix("COPERNICUS");
  cache.reset(CreateCache(michlib::GPL.ParameterSValue("Cache", "")));
+ michlib::GPL.UsePrefix(oldprefix);
  if(!cache)
  {
   michlib::errmessage("Can't init cache");