check if working dir is a directory and raise corresponding errors when making dir.

Docker-DCO-1.1-Signed-off-by: Liang-Chi Hsieh <viirya@gmail.com> (github: viirya)
Fix fish completion when having alias on awk or grep

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Merge pull request #4818 from viirya/fix_working_dir_not_dir

fix the problem when setting existing file as working dir
Merge pull request #4865 from creack/fix_fish_completion

Fix fish completion when having alias on awk or grep
initial version of cli integration tests

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Small tweaks to the hack scripts to make them simpler

Please do with this as you please (including rebasing and/or squashing it), especially under clause (c) of the DCO.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)