Fix "list" shell completion to prune duplicate release names

By definition, the "list" shell completion should list all releases, no matter
their status. Previously, if a release had multiple versions, the completion
would list it more than once. This change prunes duplicates from the
completion.

Signed-off-by: Daniel Lipovetsky <dlipovetsky@d2iq.com>

cmd/helm/list.go

@@ -209,9 +209,13 @@ func compListReleases(toComplete string, cfg *action.Configuration) ([]string, c
 	}
 
 	var choices []string
+	uniqueNames := map[string]bool{}
 	for _, res := range results {
+		if ok := uniqueNames[res.Name]; !ok {
+			uniqueNames[res.Name] = true
 			choices = append(choices, res.Name)
 		}
+	}
 
 	return choices, cobra.ShellCompDirectiveNoFileComp
 }