Deadlocks inside transactions are functionally not retryable

Even if we think the deadlocking query could be retried, the original
deadlock will have either broken or already rolled back our transaction.

Author: matthewd

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -921,8 +921,13 @@ def retryable_connection_error?(exception)
         end
 
         def retryable_query_error?(exception)
-          exception.is_a?(Deadlocked) ||
-            exception.is_a?(LockWaitTimeout)
+          # We definitely can't retry if we were inside a transaction that was instantly
+          # rolled back by this error
+          if exception.is_a?(TransactionRollbackError) && savepoint_errors_invalidate_transactions? && open_transactions > 0
+            false
+          else
+            exception.is_a?(Deadlocked) || exception.is_a?(LockWaitTimeout)
+          end
         end
 
         def backoff(counter)

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -711,12 +711,10 @@ def translate_exception(exception, message:, sql:, binds:)
         end
 
         def retryable_query_error?(exception)
-        end
-
-        def retryable_connection_error?(exception)
-          case exception
-          when PG::ConnectionBad; !exception.message.end_with?("\n")
-          end
+          # We cannot retry anything if we're inside a broken transaction; we need to at
+          # least raise until the innermost savepoint is rolled back
+          @raw_connection&.transaction_status != ::PG::PQTRANS_INERROR &&
+            super
         end
 
         def get_oid_type(oid, fmod, column_name, sql_type = "")