Don't strip the security advisory number
Without this change, the index contains entries such as:
[18 Oct 2019] DLA-1963 poppler LTS security update
[17 Oct 2019] DLA-1964 sudo LTS security update
[17 Oct 2019] DLA-1963 poppler LTS security update
This is confusing, you don't know which link is the regression update and which one is the original advisory. After this change you get:
[18 Oct 2019] DLA-1963-2 poppler LTS security update
[17 Oct 2019] DLA-1964-1 sudo LTS security update
[17 Oct 2019] DLA-1963-1 poppler LTS security update
I consider the later to be least confusing.