Copy some of the initialisation from (guix git)

To go along with just-update-cached-checkout.

guix-data-service/poll-git-repository.scm

@@ -22,11 +22,7 @@
   #:use-module (srfi srfi-71)
   #:use-module (ice-9 threads)
   #:use-module (squee)
-  #:use-module (git oid)
-  #:use-module (git branch)
-  #:use-module (git remote)
-  #:use-module (git reference)
-  #:use-module (git repository)
+  #:use-module (git)
   #:use-module (guix git)
   #:use-module (guix channels)
   #:use-module (guix-data-service database)
@@ -39,6 +35,9 @@
 (define (start-thread-to-poll-git-repository git-repository-id)
   (call-with-new-thread
    (lambda ()
+     (libgit2-init!)
+     (honor-system-x509-certificates!)
+
      (with-postgresql-connection
       (simple-format #f "poll-git-repository-~A"
                      git-repository-id)