Causes the next call to the EncoderExceptionFallbackBuffer.GetNextChar method to access the exception data buffer character position that is prior to the current position.
The return value is always false.
A return value is defined, although it is unchanging, because this method implements an abstract method.
Because System.Text.EncoderExceptionFallbackBuffer has no actual exception data buffer, the EncoderExceptionFallbackBuffer.MovePrevious method always returns false.