error: 'isfolder' undefined

[florisvb]

I am getting this error when running octave gocal.m with my own data, as well as all three of the test datasets. Any idea what is happening?

caveman@RiffellCave1:~/big_tunnel_calibration_test/latest/MultiCamSelfCal/MultiCamSelfCal$ octave gocal.m --config=/home/caveman/big_tunnel_calibration_test/latest/MultiCamSelfCal/strawlab/test-data/caldata20130726_122220 warning: function ../CalTechCal/quiver.m shadows a core library function warning: called from gocal.m at line 23 column 1 arg = --config=/home/caveman/big_tunnel_calibration_test/latest/MultiCamSelfCal/strawlab/test-data/caldata20130726_122220 error: 'isfolder' undefined near line 14 column 4 error: called from read_generic_configuration at line 14 column 1 read_configuration at line 43 column 8 gocal.m at line 26 column 8

I do not get this error on an older commit: 94e0bb2a479546d0af6bf29a3681aae7be08daf9