I tried adding vu.set_sim_option('ghdl.gtkwave_script.gui', 'addWave.tcl') to my run.py, where addWave.tcl is #455 (comment). It fails with:

GTKWave Analyzer v3.3.101 (w)1999-2019 BSI

[0] start time.
[1400000000] end time.
GTKWAVE | Executing Tcl script '"/src/addWave.tcl"'
GTKWAVE | couldn't read file ""/src/addWave.tcl"": no such file or directory
WM Destroy

However, if I replace https://github.com/VUnit/vunit/blob/master/vunit/ghdl_interface.py#L276 with cmd += ["--script", "{}".format(abspath(init_file))], it works as expected.

@GlenNicholls, might those additional double quotes be platform-dependent?