_yaml.pyx: Forbid expected_type=Mapping, and remove isinstance check

Calls to `isinstance` can be particularily costly. Using type() is
much faster. The only known case where the `isinstance` was useful
is for dictionnaries where we would ask for a 'Mapping' instead.

Disallowing 'Mapping' for expected_type considerably speeds up the
calls to this functions.

Also add into NEWS

1 files changed, 2 insertions, 3 deletions

diff --git a/doc/bst2html.py b/doc/bst2html.py
index 2f4012695..448ab1389 100755
--- a/doc/bst2html.py
+++ b/doc/bst2html.py
@@ -29,7 +29,6 @@ import sys
 import re
 import shlex
 import subprocess
-from collections.abc import Mapping
 from contextlib import contextmanager
 from tempfile import TemporaryDirectory
 
@@ -348,7 +347,7 @@ def run_session(description, tempdir, source_cache, palette, config_file, force)
     #        tarball. This workaround lets us build docs from
     #        a source distribution tarball.
     #
-    symlinks = _yaml.node_get(desc, Mapping, 'workaround-symlinks', default_value={})
+    symlinks = _yaml.node_get(desc, dict, 'workaround-symlinks', default_value={})
     for symlink, target in _yaml.node_items(symlinks):
 
         # Resolve real path to where symlink should be
@@ -382,7 +381,7 @@ def run_session(description, tempdir, source_cache, palette, config_file, force)
     #
     commands = _yaml.node_get(desc, list, 'commands')
     for c in commands:
-        command = _yaml.node_get(desc, Mapping, 'commands', indices=[commands.index(c)])
+        command = _yaml.node_get(desc, dict, 'commands', indices=[commands.index(c)])
 
         # Get the directory where this command should be run
         directory = _yaml.node_get(command, str, 'directory')