It is easy to understand why the existing code (usually) fails: 

  * Users are most likely to just specify short names, like "dolphin,gwenview,okular,rekonq", instead of "/usr/bin/konsole,/usr/bin/gwenview,/usr/bin/okular,/usr/bin/rekonq"

 * When ksmserver saves the session, it usually gets the full names, like "/usr/bin/dolphin", unless you have started that dolphin instance by typing "dolphin" exactly in a shell. 


So there are four possible combinations :

  1). config uses short name, runtime gets short name (this guy starts everything from konsole, never using kio/krun)
  2). config uses short name, runtime gets long name (I think this is the most common one)
  3). config uses long name, runtime gets short name 
  4). config uses long name, runtime gets long name (I guess some users use this combination because they find only that way works after trying various workaround...)

The existing code works with 1) and 4), the patch now works  with 1), 2) and 4) . I don't know whether it make senses to support all combinations .