fix(telephony): rollback before logging in call_log link_existing_conversations (Postgres)

The hook saves Call Logs in a loop; on failure the except calls frappe.log_error (INSERT) with no rollback, raising InFailedSqlTransaction on Postgres (it runs on every Contact create/update). Full frappe.db.rollback() before log_error. No-op on MariaDB.

erpnext/telephony/doctype/call_log/call_log.py

@@ -196,6 +196,7 @@ def link_existing_conversations(doc, state):
 				if not frappe.in_test:
 					frappe.db.commit()
 	except Exception:
+		frappe.db.rollback()
 		frappe.log_error(title=_("Error during caller information update"))