set clipboard=unnamed in .vimrc is ignored

• Specify a .vimrc with set clipboard=unnamed (or set clipboard=unnamedplus) in FakeVim options
• Restart QtCreator
• Select a line with shift+v, copy it with y => System buffer is not filled in (try to paste this line to another program)

• Execute FakeVIm command :set clipboard=unnamed in QtCreator
• Select a line with shift+v, copy it with y => System buffer is now filled in

This is a regression breaking QTCREATORBUG-6342, likely introduced in 6.0.0.