PYTHON-5677 Prevent ClientEncryption from loading crypt shared library (#2659)

Co-authored-by: Kevin Albertson <kevin.albertson@mongodb.com>

doc/changelog.rst

@@ -17,6 +17,9 @@ PyMongo 4.16 brings a number of changes including:
 - Fixed return type annotation for ``find_one_and_*`` methods on :class:`~pymongo.asynchronous.collection.AsyncCollection`
   and :class:`~pymongo.synchronous.collection.Collection` to include ``None``.
 - Added support for NumPy 1D-arrays in :class:`bson.binary.BinaryVector`.
+- Prevented :class:`~pymongo.encryption.ClientEncryption` from loading the crypt
+  shared library to fix "MongoCryptError: An existing crypt_shared library is
+  loaded by the application" unless the linked library search path is set.
 
 Changes in Version 4.15.5 (2025/12/02)
 --------------------------------------

pymongo/asynchronous/encryption.py

@@ -717,7 +717,10 @@ class AsyncClientEncryption(Generic[_DocumentType]):
         self._encryption = AsyncExplicitEncrypter(
             self._io_callbacks,
             _create_mongocrypt_options(
-                kms_providers=kms_providers, schema_map=None, key_expiration_ms=key_expiration_ms
+                kms_providers=kms_providers,
+                schema_map=None,
+                key_expiration_ms=key_expiration_ms,
+                bypass_encryption=True,  # Don't load crypt_shared
             ),
         )
         # Use the same key vault collection as the callback.

pymongo/synchronous/encryption.py

@@ -710,7 +710,10 @@ class ClientEncryption(Generic[_DocumentType]):
         self._encryption = ExplicitEncrypter(
             self._io_callbacks,
             _create_mongocrypt_options(
-                kms_providers=kms_providers, schema_map=None, key_expiration_ms=key_expiration_ms
+                kms_providers=kms_providers,
+                schema_map=None,
+                key_expiration_ms=key_expiration_ms,
+                bypass_encryption=True,  # Don't load crypt_shared
             ),
         )
         # Use the same key vault collection as the callback.