files remaining open after OGR reads SDTS vectors

[bdiscoe]

I am attempting to add support for reading SDTS files directly from 
their archive, e.g. "FOO.sdts.tar.gz". To do this, my application 
expands the archive into a temporary folder, finds the CATD file, 
reads the data with OGR, then attempts to delete the temporary files.

However, of the 22 files in my SDTS 'transfer', 8 of them are 
refusing to be deleted after OGR has finished reading them:

AHDR.DDF
ARDF.DDF
ARDM.DDF
LE01.DDF
NA01.DDF
NO01.DDF
NP01.DDF
PC01.DDF

I think this is because OGR is forgetting to close the files. As far 
i can tell i am doing everything correctly:

OGRDataSource *datasource = OGRSFDriverRegistrar::Open(fname);
// (read the data from the layers)
delete datasource;

Is there something else i need to do so that the files get closed 
properly? Or is this a bug?

Thanks,
Ben