pw-apply: Trim leading dash from branch name

Otherwise git commands will fail badly, when the branch name matches
such pattern, e.g.:

  https://patchwork.kernel.org/user/todo/netdevbpf/?series=640543

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
1 file changed