Duplicate "unknown flag" output

[akupila]

With a recent version of Cobra duplicate output is printed when unknown flags are passed:

package main

import "github.com/spf13/cobra"

func main() {
	cmd := &cobra.Command{
		Use: "cobratest",
	}
	cmd.Execute()
}

Running cobratest --test prints:

unknown flag: --test
Usage of cobratest:
  -h, --help   help for cobratest
Error: unknown flag: --test
Usage:

I did some digging and found that this was introduced in b655df6. With a version of cobra prior to this the output for the same command is:

Error: unknown flag: --test
Usage:

[n10v]

Thank you for your bug report and sorry for the inconvenience! I fixed it.
Please update cobra and its dependencies:go get -u github.com/spf13/cobra