QA 1100: handle missing commands from pcp-gui
QA 1100: handle missing commands from pcp-gui

pcp-gui is not necessarily available on all platforms, tolerate
its absence (this test case is about platform-agnostic shell
completions so no downsides with this approach).

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp