| Bugfix | |
| * In the bignum module, operations of the form (-A) - (+A) or (-A) - (-A) | |
| with A > 0 created an unintended representation of the value 0 which was | |
| not processed correctly by some bignum operations. Fix this. This had no | |
| consequence on cryptography code, but might affect applications that call | |
| bignum directly and use negative numbers. |