fix "podman -h" help output

`podman -h` currently returns an error:
`Error: pflag: help requested`

This bug was introduced in 44d037898e, the problem is that we wrap the
error and cobra lib checks with `==` for this one and not errors.Is().
I have a PR upstream to fix this but for now this also works.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

cmd/podman/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -26,6 +27,7 @@ import (
 	"github.com/containers/storage/pkg/reexec"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 )
 
 func main() {
@@ -101,6 +103,13 @@ func parseCommands() *cobra.Command {
 }
 
 func flagErrorFuncfunc(c *cobra.Command, e error) error {
+	// cobra compares via == and not errors.Is so we cannot wrap that error.
+	// This is required to make podman -h work.
+	// This can be removed once https://github.com/spf13/cobra/pull/1730
+	// is merged and vendored into podman.
+	if errors.Is(e, pflag.ErrHelp) {
+		return e
+	}
 	e = fmt.Errorf("%w\nSee '%s --help'", e, c.CommandPath())
 	return e
 }