Rename _rebind_query_planner to _export_query_planner

The method rebinds nothing. It imports whatever a `__datafusion_session_planner__`
hook returned — an object exposing the getter or a raw capsule — and hands back a
capsule, so the next hook receives one either way; its own doc comment already
said "re-export". Meanwhile "rebind" means something specific and different in
this file: rebuilding an installed planner against a handle's codec chains, which
is what `set_session_query_planner` does. Freeing the word keeps the two apart.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: timsaucer

crates/core/src/context.rs

@@ -1688,7 +1688,7 @@ impl PySessionContext {
     /// not have to branch on which. Importing here also surfaces a malformed
     /// planner at the hook that produced it rather than at the final install.
     /// Writes nothing.
-    pub fn _rebind_query_planner<'py>(
+    pub fn _export_query_planner<'py>(
         slf: &Bound<'py, Self>,
         planner: Bound<'py, PyAny>,
     ) -> PyDataFusionResult<Bound<'py, PyCapsule>> {

python/datafusion/context.py

@@ -1986,7 +1986,7 @@ class as :py:meth:`with_logical_extension_codec` describes. Declare
             supplied = extension.__datafusion_session_planner__(new, fallback)
             if supplied is None:
                 continue
-            planner = new.ctx._rebind_query_planner(supplied)
+            planner = new.ctx._export_query_planner(supplied)
 
         # Rebinding the session's planner is a side effect on state shared with
         # every other handle, so do not pay it for a call that installs nothing

python/tests/test_wrapper_coverage.py

@@ -33,11 +33,11 @@
 # gap in coverage.
 PRIVATE_SUPPORT_METHODS = frozenset(
     {
-        # The three phases of SessionContext.with_extensions: install the
-        # codecs, normalize each planner hook's return value, commit the
-        # planner.
+        # The three steps of SessionContext.with_extensions: install the
+        # codecs, re-export each planner hook's return value as a capsule,
+        # commit the planner.
         "_install_extension_codecs",
-        "_rebind_query_planner",
+        "_export_query_planner",
         "_install_extension_planner",
     }
 )