rust: disable the RustIndex without persistent nodemap

See rational inline.

mercurial/revlog.py

@@ -1678,14 +1678,15 b' class revlog:'
         )
 
         use_rust_index = False
-        if rustrevlog is not None:
-            if self._nodemap_file is not None:
-                use_rust_index = True
-            else:
-                # Using the CIndex is not longer possible, as the
-                # `AncestorsIterator` and `LazyAncestors` classes now require
-                # a Rust index for instantiation.
-                use_rust_index = True
+        if rustrevlog is not None and self._nodemap_file is not None:
+            # we would like to use the rust_index in all case, especially
+            # because it is necessary for AncestorsIterator and LazyAncestors
+            # since the 6.7 cycle.
+            #
+            # However, the performance impact of inconditionnaly building the
+            # nodemap is currently a problem for non-persistent nodemap
+            # repository.
+            use_rust_index = True
 
         self._parse_index = parse_index_v1
         if self._format_version == REVLOGV0:

tests/test-verify.t

@@ -311,8 +311,7 b' test revlog corruption'
   $ cat start b > .hg/store/data/a.i
 
   $ hg verify -q
-   a@1: broken revlog! (index a is corrupted) (no-rust !)
-   a@1: broken revlog! (abort: unexpected inline revlog length) (rust !)
+   a@1: broken revlog! (index a is corrupted)
   warning: orphan data file 'data/a.i'
   not checking dirstate because of previous errors
   1 warnings encountered!