largefiles: take lock before writing requirements

With `share-safe`, we will also write file in the store. We now take the `lock`
as needed.

Differential Revision: https://phab.mercurial-scm.org/D11992

hgext/largefiles/reposetup.py

@@ -455,11 +455,12 b' def reposetup(ui, repo):'
     repo.prepushoutgoinghooks.add(b"largefiles", prepushoutgoinghook)
 
     def checkrequireslfiles(ui, repo, **kwargs):
-        if b'largefiles' not in repo.requirements and any(
-            lfutil.shortname + b'/' in f[1] for f in repo.store.datafiles()
-        ):
-            repo.requirements.add(b'largefiles')
-            scmutil.writereporequirements(repo)
+        with repo.lock():
+            if b'largefiles' not in repo.requirements and any(
+                lfutil.shortname + b'/' in f[1] for f in repo.store.datafiles()
+            ):
+                repo.requirements.add(b'largefiles')
+                scmutil.writereporequirements(repo)
 
     ui.setconfig(
         b'hooks', b'changegroup.lfiles', checkrequireslfiles, b'largefiles'