Location CCK creates empty locations

The Location CCK attempts to not create empty locations if no location information is provided. This works when creating nodes programmatically or via an import. However a cck node created or edited using the normal pages node/add/content_type and node/nnn/edit will create an empty location and attached it to the node even if the location is 'empty'.

The problem occurrs because of the Location CCK element 'cck_preview_in_progress'. This only appears in the location cck form and is not known to the location module that handles the empty location detection. To detect an empty location the location module builds an empty location in location_empty_location and then compares it against the provided location in location_calc_difference. To build the empty location the routine uses the defaults provided by calls to hook_locationapi but location_cck does not provide any defaults for cck_preview_in_progress. So the provided location includes cck_preview_in_progress but the empty location does not and the difference is found by location_calc_difference and the location determined to be 'not empty'.

There are two possible fixes, provide a default value for cck_preview_in_progress in location_cck_locationapi, which is probably good practice anyway, OR tell location_calc_difference that cck_preview_in_progress is unimportant when calculating the difference. The latter is done by setting the 'nodiff' flag, again in location_cck_locationapi.

Either solution should work and its probably best to implement both. However the 'nodiff' flag failed. The problem this time was in location_strip that removes the unimportant fields from a location. When deciding whether to strip it uses the line:
if(!($location[$k] == "locpick" || $location[$k] == "user_latitude" || $location[$k] == "user_longitude")) {
When $k was cck_prevoew_in_progress and $location[$k] = TRUE this returned false and the field was not stripped. I think this line should read:
if(!($k == "locpick" || $k == "user_latitude" || $k == "user_longitude")) {
as it is the keys we want to compare and not the field values.

So there are three fixes required:
1. Provide a default for cck_preview_in_progress in location_cck_locationapi
2. Add the 'nodiff' flag for cck_preview_in_progress in location_cck_locationapi
3. Fix location_strip in location.module to test keys rather than values.