"Last Change" in Implementer's Guide is broken

[mrcnski]

ISSUE

Overview

The new "last change" feature is not working (see footer):

https://paritytech.github.io/polkadot/book/pvf-prechecking.html

I believe this is because in GitLab CI we have a git depth of 100, so it is not getting the full commit history. See line 14:

https://gitlab.parity.io/parity/mirrors/polkadot/-/jobs/2042805

Proposed Change(s)

1. Do a full git clone for the build-implementers-guide job only (might be fine if we only do this on PR merge?) (are there any speed/memory restrictions on GitLab CI?) cc @paritytech/ci @sergejparity

2. Or, scrap this feature if we don't have access to the full history.

[mrcnski]

Reopening as the issue seems to be persisting.

Looking at the build job it seems that the git depth is no longer being reported at 100:
https://gitlab.parity.io/parity/mirrors/polkadot/-/jobs/2059294

Not sure what the issue could be, maybe someone at @paritytech-ci has some ideas?