Fix minor bug in --host-groups flag completion

The previous completion would suggest completions given host groups in a
file when `<tab>``<tab>`-ing after the `--host-groups` or `-g` flag, but
if the user started typing the name of a group, the suggestions would
not continue to be filled in.

Take the overide flags behavior directly from kubectl's custom command
definition, and use that since it implements the behavior already. This
function is probably a bit overkill for Octopus' simple needs, but it
works.

Signed-off-by: Blaine Gardner <blaine.gardner@suse.com>

cmd/octopus/config/cli.go

@@ -84,18 +84,42 @@ __octopus_empty_completion()
 	COMPREPLY+=("" " ")
 }
 
-__octopus_current_flags()
+# taken from kubectl; override flags are flags that need to be present when running octopus to get
+# completion suggestions for other flags because they change the behavior of octopus.
+# specifically, groups-file changes the groups available to octopus for getting completion for the
+# host-groups flag
+__octopus_override_flag_list=(--groups-file -f)
+__octopus_override_flags()
 {
-	local flags
-	flags=(${words[@]:1}) # do not include 'octopus' cmd itself
-	unset -v 'flags[${#flags[@]}-1]'
-	echo "${flags[*]}"
+    local ${__octopus_override_flag_list[*]##*-} two_word_of of var
+    for w in "${words[@]}"; do
+        if [ -n "${two_word_of}" ]; then
+            eval "${two_word_of##*-}=\"${two_word_of}=\${w}\""
+            two_word_of=
+            continue
+        fi
+        for of in "${__octopus_override_flag_list[@]}"; do
+            case "${w}" in
+                ${of}=*)
+                    eval "${of##*-}=\"${w}\""
+                    ;;
+                ${of})
+                    two_word_of="${of}"
+                    ;;
+            esac
+        done
+    done
+    for var in "${__octopus_override_flag_list[@]##*-}"; do
+        if eval "test -n \"\$${var}\""; then
+            eval "echo \${${var}}"
+        fi
+    done
 }
 
 __octopus_get_host_groups()
 {
 	local out
-	if out=$(octopus $(__octopus_current_flags) host-groups); then
+	if out=$(octopus $(__octopus_override_flags) host-groups); then
 		if [[ -n "$out" ]]; then
 			COMPREPLY+=( $( compgen -W "${out[*]}" -- "$cur" ) )
 		else