Steps to reproduce:

1. Import some FCS files
2. Import a tsv file with sample set data (with just one row referencing one signle FCS file)
3. Join the FCS files to the sample set from 2. (by specifying the join fields)
4. Append the sample set above with another one (with just one row, but referencing a different FCS file)

Expected result: the set of joined FCS files should now be of size 2
Observed result: the set of joined FCS files is still of size 1

SVN revision: 33495

Thanks.