Adds a new entry to this, replacing replace_name and replace_email with
real_name and real_email respectively.
If replace_name is null, it is ignored during matching. If either real_name
or real_email is null, the respective field is not replaced.
| this |
the mailmap to add the entry in. |
| real_name |
the real name of the person. |
| real_email |
the real email of the person. |
| replace_name |
the name to replace. |
| replace_email |
the email to replace. |