bug#55326: libgit2 1.3.0 includes a time-dependent test

["Ludovic Courtès" <ludo@gnu.org>]

libgit2 1.3.0 (and 1.4.3, it seems) includes a time-dependent test:
‘refs::revparse::date’, in ‘tests/refs/revparse.c’, assumes
“HEAD@{10 years ago}” doesn't match anything in the sample repositories,
which is no longer true:

--8<---------------cut here---------------start------------->8---
$ date
Sun May  8 11:04:31 PM CEST 2022
$ ./libgit2_clar -v -Q -srefs::revparse::date
Loaded 404 suites: 
Started (test status codes: OK='.' FAILURE='F' SKIPPED='S')

refs::revparseF

  1) Failure:
refs::revparse::date [/tmp/guix-build-libgit2-1.3.0.drv-0/source/tests/refs/revparse.c:31]
  Function call succeeded: error
  no error, expected non-zero return

$ /gnu/store/wy3ww7znqhlg84vg6cmw1m12z1drxwh1-libfaketime-0.9.9/bin/faketime 2021-12-12 ./libgit2_clar -v -Q -srefs::revparse::date
Loaded 404 suites: 
Started (test status codes: OK='.' FAILURE='F' SKIPPED='S')

refs::revparse.

--8<---------------cut here---------------end--------------->8---

Thus, as of 6b588da368c77cde82ea2f22ca315116228777ad, libgit2 now fails
to build; a few months ago, it would build fine.

Ludo’.