lfs: migrate to the fileprefetch callback mechanism

hgext/lfs/__init__.py

@@ -334,7 +334,8 b' def extsetup(ui):'
     wrapfunction(hg, 'postshare', wrapper.hgpostshare)
 
     wrapfunction(merge, 'applyupdates', wrapper.mergemodapplyupdates)
-    wrapfunction(cmdutil, '_prefetchfiles', wrapper.cmdutilprefetchfiles)
+
+    scmutil.fileprefetchhooks.add('lfs', wrapper._prefetchfiles)
 
     # Make bundle choose changegroup3 instead of changegroup2. This affects
     # "hg bundle" command. Note: it does not cover all bundle formats like

hgext/lfs/wrapper.py

@@ -266,12 +266,6 b' def _prefetchfiles(repo, ctx, files):'
     if pointers:
         repo.svfs.lfsremoteblobstore.readbatch(pointers, localstore)
 
-def cmdutilprefetchfiles(orig, repo, ctx, files):
-    """Prefetch the indicated files before they are accessed by a command."""
-    orig(repo, ctx, files)
-
-    _prefetchfiles(repo, ctx, files)
-
 def mergemodapplyupdates(orig, repo, actions, wctx, mctx, overwrite,
                          labels=None):
     """Ensure that the required LFS blobs are present before applying updates,