Hi,
one of the recent patches related to the changes of the sysdb calls to return ENOENT broke the flow in the lookups by SID. As a result the request always returned if no result was found in the cache instead of asking the backend. With the new flow the ldb_result has to be properly initialized (I remember there was a long discussion about it, but I can't remember the result, so I fixed it in the caller).
The verify this you need just to look up a SID with is currently not in the cache, the easiest way is to use an empty cache:
python -c "import pysss_nss_idmap; print pysss_nss_idmap.getnamebysid('S-1-5-21-3456664713-2053453454-4165325232-500')"
Without the patch only an empty list is return, with the patch the SID is properly looked up by the backend.
bye, Sumit