Mailmap with empty email address is not parsed

[pulkomandy]

Environment:

• Debian sid
• Python 3.11.6
• libgit2-1.7.1+ds-2
• pygit2 1.13.3-1+b1

Test case:

from pygit2 import Mailmap
Mailmap.from_buffer("RealName <real.address@domain.com> oldname <>")

Result:

ValueError: invalid argument: 'replace_email && *replace_email'

Expected result:

This syntax is accepted by Git (mapped names are shown in git log). Empty emails should be allowed.