message: Builder: remove has_xattr flag check for merge
  The `has_xattr` flag is not a user-specified by builder (nydus-image),
  the flag value is calculated by checking whether if have any files have
  xattr, so for bootstrap merge scenario, we can't assume this value is
  same between different bootstraps.
diff: @@ -23,7 +23,6 @@ use crate::core::tree::{MetadataTreeBuilder, Tree};
  #[derive(Clone, Debug, Eq, PartialEq)]
  struct Flags {
  explicit_uidgid: bool,
  - has_xattr: bool,
  compressor: compress::Algorithm,
  digester: digest::Algorithm,
  }
  @@ -32,7 +31,6 @@ impl Flags {
  fn from_meta(meta: &RafsSuperMeta) -> Self {
  Self {
  explicit_uidgid: meta.explicit_uidgid(),
  - has_xattr: meta.has_xattr(),
  compressor: meta.get_compressor(),
  digester: meta.get_digester(),
  }
  @@ -40,7 +38,6 @@ impl Flags {
  fn set_to_ctx(&self, ctx: &mut BuildContext) {
  ctx.explicit_uidgid = self.explicit_uidgid;
  - ctx.has_xattr = self.has_xattr;
  ctx.compressor = self.compressor;
  ctx.digester = self.digester;
  }
  @@ -93,9 +90,10 @@ impl Merger {
  if let Some(flags) = &flags {
  if flags != &current_flags {
  bail!(
  - "inconsistent flags between bootstraps, current bootstrap {:?}, flags {:?}",
  + "inconsistent flags between bootstraps, current bootstrap {:?}, flags {:?}, expected flags {:?}",
  bootstrap_path,
  current_flags,
  + flags,
  );
  }
  } else {
  