lfs: consult the narrow matcher when extracting pointers from ctx (issue5794)

I added a testcase for lfs to all narrow tests, and the following failed:

    test-narrow-acl.t
    test-narrow-exchange.t
    test-narrow-patterns.t
    test-narrow-strip.t
    test-narrow-trackedcmd.t
    test-narrow-widen.t
    test-narrow.t

The first two still have errors in the pretxnchangegroup on clone and (receiving
a) push, which I'm still looking into (4d63f3bc1e1a fixed something in this area
already).  These two modified tests seem to cover the things that failed in the
remaining narrow tests, i.e. `hg tracked` and `hg strip`, so I didn't bother
enabling the testcases elsewhere.  Maybe we should, but it's 68 tests total.

hgext/lfs/wrapper.py

@@ -374,7 +374,12 b' def pointersfromctx(ctx, removed=False):'
     stored for the path is an empty dict.
     """
     result = {}
+    m = ctx.repo().narrowmatch()
+
+    # TODO: consider manifest.fastread() instead
     for f in ctx.files():
+        if not m(f):
+            continue
         p = pointerfromctx(ctx, f, removed=removed)
         if p is not None:
             result[f] = p

tests/test-narrow-strip.t

@@ -1,4 +1,12 b''
 #testcases flat tree
+#testcases lfs-on lfs-off
+
+#if lfs-on
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > lfs =
+  > EOF
+#endif
 
   $ . "$TESTDIR/narrow-library.sh"
 

tests/test-narrow.t

@@ -1,4 +1,12 b''
 #testcases flat tree
+#testcases lfs-on lfs-off
+
+#if lfs-on
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > lfs =
+  > EOF
+#endif
 
   $ . "$TESTDIR/narrow-library.sh"