Update libgit2 to 0.28.1

ethomson · ethomson · commit d0a252153df6 · 2019-02-14T19:52:48.000Z
diff --git a/libgit2 b/libgit2
@@ -1 +1 @@
-Subproject commit 1a107fac0fc88a4d74b64ffc9ae2fd178ba631c0
+Subproject commit 572e4d8c1f1d42feac1c770f0cddf6fda6c4eca0
