Searching inside a country

The geocoder in our software suddenly stopped working and we have analyzed this to the following cause: To search for the Mainstreet 12, Amsterdam, Netherlands, (doesn't exist) we used the following call:

http://nominatim.openstreetmap.org/search?q=12,Mainstreet,Amsterdam,NL&format=xml

This format used to work but no longer returns results. I noticed that it does work with the full country name appended to the address

http://nominatim.openstreetmap.org/search?q=12,Mainstreet,Amsterdam,Nederland&format=xml

but we don't have the country name available in our software. So, now I plan to change our code to

http://nominatim.openstreetmap.org/search?q=12,Mainstreet,Amsterdam&countryCodes=NL&format=xml

Since that is in line with the wiki description.

My main questions are. Did the API indeed change? How could I have known this upfront, so where should I register to be warned for such changes before they become effective?