gff3_merge user-defined file option does not work in python 3

[mpoelchau]

When using gff3_merge, I had to use the user-defined file option. The sequence extraction and blast seemed to run fine, but the replacement still didn't work. I tried the same command with a python 2 installation and the expected models were replaced.

The dataset I was working with is private, so I can't post it - but I will keep it around until we have capacity to fix this (probably in February).