rust-nodemap-docket: move check of nodemap requirement to caller

I think it's cleaner if `NodeMapDocket` doesn't know about the `Repo`
type. That makes it more easily reusable and testable. This patch
moves out one of the uses of `Repo` out of it.

Differential Revision: https://phab.mercurial-scm.org/D12544

rust/hg-core/src/revlog/nodemap_docket.rs

@@ -1,5 +1,4 b''
 use crate::errors::{HgError, HgResultExt};
-use crate::requirements;
 use bytes_cast::{unaligned, BytesCast};
 use memmap2::Mmap;
 use std::path::{Path, PathBuf};
@@ -38,14 +37,6 b' impl NodeMapDocket {'
         repo: &Repo,
         index_path: &Path,
     ) -> Result<Option<(Self, Mmap)>, HgError> {
-        if !repo
-            .requirements()
-            .contains(requirements::NODEMAP_REQUIREMENT)
-        {
-            // If .hg/requires does not opt it, don’t try to open a nodemap
-            return Ok(None);
-        }
-
         let docket_path = index_path.with_extension("n");
         let docket_bytes = if let Some(bytes) =
             repo.store_vfs().read(&docket_path).io_not_found_as_none()?

rust/hg-core/src/revlog/revlog.rs

@@ -18,7 +18,7 b' use super::patch;'
 use crate::errors::HgError;
 use crate::repo::Repo;
 use crate::revlog::Revision;
-use crate::{Node, NULL_REVISION};
+use crate::{requirements, Node, NULL_REVISION};
 
 const REVISION_FLAG_CENSORED: u16 = 1 << 15;
 const REVISION_FLAG_ELLIPSIS: u16 = 1 << 14;
@@ -111,6 +111,12 b' impl Revlog {'
 
         let nodemap = if index.is_inline() {
             None
+        } else if !repo
+            .requirements()
+            .contains(requirements::NODEMAP_REQUIREMENT)
+        {
+            // If .hg/requires does not opt it, don’t try to open a nodemap
+            None
         } else {
             NodeMapDocket::read_from_file(repo, index_path)?.map(
                 |(docket, data)| {