[PATCH 4 of 6 V2] cat: migrate to the fileprefetch callback mechanism

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1518328282 18000
#      Sun Feb 11 00:51:22 2018 -0500
# Node ID 386c98fec8ab751dfa6dc7fd7a83ecc2c5d6815b
# Parent  0994666ab1003686784ee4f491a716f0199a1577
cat: migrate to the fileprefetch callback mechanism

diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -2187,14 +2187,14 @@
         mfnode = ctx.manifestnode()
         try:
             if mfnode and mfl[mfnode].find(file)[0]:
-                _prefetchfiles(repo, ctx, [file])
+                fileprefetchhooks(repo, ctx, [file])
                 write(file)
                 return 0
         except KeyError:
             pass
 
     files = [f for f in ctx.walk(matcher)]
-    _prefetchfiles(repo, ctx, files)
+    fileprefetchhooks(repo, ctx, files)
 
     for abs in files:
         write(abs)