ck-history truncates most login names at my place of work and customer sites because of a hard coded length restriction of 8 characters. The length restriction should be removed or increased to a high enough value that only a tiny percentage of users would be affected. Note that POSIX has LOGIN_NAME_MAX in limits.h and that 8 characters is the minimum length a POSIX compliant system can support (http://pubs.opengroup.org/onlinepubs/007908799/xsh/limits.h.html).
At my installation and many customer sites, the login name uses the first letter of the first name and the full last name (and some sites use the full first and last names). Using statistics that others have gathered (google average length of last name), half of last names are more than 6 characters. This means ck-history will truncate around half of user names.
Additionally, users of OpenLDAP, Likewise Open, and other directory access mechanisms will almost always be affected as the initial portion of the login name contains a domain/realm and separator character.