bug#55462: emacs-libgit tests fail

[Jack Hill <jackhill@jackhill.us>]

Hi Guix,

With Guix 76cc5b9e806635cfb94a2c1101ffe6500eab6976 the emacs-libgit tests 
fail as follows:

```
Test project /tmp/guix-build-emacs-libgit-20200515-1.0ef8b13.drv-0/build
       Start  1: libegit2_annotated-commit
  1/29 Test  #1: libegit2_annotated-commit ........   Passed    0.31 sec
       Start  2: libegit2_blame
  2/29 Test  #2: libegit2_blame ...................   Passed    0.34 sec
       Start  3: libegit2_blob
  3/29 Test  #3: libegit2_blob ....................***Failed    0.35 sec
Running 4 tests (2022-05-15 11:48:12+0000, selector ?t?)
Test blob-binary backtrace:
   signal(wrong-type-argument (utf-8-string-p "\177ELF\2\1\1\0\0\0\0\0\
   apply(signal (wrong-type-argument (utf-8-string-p "\177ELF\2\1\1\0\0
   (setq value-42 (apply fn-40 args-41))
   (unwind-protect (setq value-42 (apply fn-40 args-41)) (setq form-des
   (if (unwind-protect (setq value-42 (apply fn-40 args-41)) (setq form
   (let (form-description-44) (if (unwind-protect (setq value-42 (apply
   (let ((value-42 'ert-form-evaluation-aborted-43)) (let (form-descrip
   (let* ((fn-40 #'string=) (args-41 (condition-case err (let ((signal-
   (let* ((repo (libgit-repository-open path)) (blob (libgit-revparse-s
   (let ((default-directory path)) (init) (commit-change "filename" str
   (progn (make-directory path 'parents) (let ((default-directory path)
   (unwind-protect (progn (make-directory path 'parents) (let ((default
   (let ((path "/tmp/guix-build-emacs-libgit-20200515-1.0ef8b13.dr...")
   (let* ((str (unibyte-string 127 69 76 70 2 1 1 0 0 0 0 0 0 0 0 0 3 0
   (let ((lexical-binding nil)) (let* ((str (unibyte-string 127 69 76 7
   (lambda nil (let ((lexical-binding nil)) (let* ((str (unibyte-string
   ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
   ert-run-test(#s(ert-test :name blob-binary :documentation nil :body
   ert-run-or-rerun-test(#s(ert--stats :selector t :tests [#s(ert-test
   ert-run-tests(t #f(compiled-function (event-type &rest event-args) #
   ert-run-tests-batch(nil)
   ert-run-tests-batch-and-exit()
   command-line-1(("-L" "/tmp/guix-build-emacs-libgit-20200515-1.0ef8b1
   command-line()
   normal-top-level()
Test blob-binary condition:
     (wrong-type-argument utf-8-string-p "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260\7\0\0\0\0\0\0@\0\0\0\0\0\0\0\270\33\0\0\0\0\0\0\0\0\0\0@\08\0\11\0@\0\35\0\34\0\6\0\0\0\5\0\0\0@\0\0\0\0\0\0\0")
    FAILED  1/4  blob-binary (0.024184 sec)
    passed  2/4  blob-create-fromdisk (0.012522 sec)
    passed  3/4  blob-create-fromstring (0.011408 sec)
    passed  4/4  blob-text (0.022810 sec)

Ran 4 tests, 3 results as expected, 1 unexpected (2022-05-15 11:48:12+0000, 0.230686 sec)

1 unexpected results:
    FAILED  blob-binary
```

Best,
Jack