[PATCH 2 of 2] cat: do not instantiate subrepo if no potential match in it

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1511593310 -32400
#      Sat Nov 25 16:01:50 2017 +0900
# Node ID b6e526ee5d2662ca30a555ca51264b3e371fe44e
# Parent  38e952030f0c4746257280d47f0f94b6cb9ddb41
cat: do not instantiate subrepo if no potential match in it

This fixes the test failure in hg-git.

https://bitbucket.org/durin42/hg-git/issues/227/

diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -3068,6 +3068,8 @@ def cat(ui, repo, ctx, matcher, basefm, 
         err = 0
 
     for subpath in sorted(ctx.substate):
+        if not matcher.visitdir(subpath):
+            continue
         sub = ctx.sub(subpath)
         try:
             submatch = matchmod.subdirmatcher(subpath, matcher)
diff --git a/tests/test-subrepo.t b/tests/test-subrepo.t
--- a/tests/test-subrepo.t
+++ b/tests/test-subrepo.t
@@ -1081,6 +1081,36 @@ Prepare a repo with subrepo
   $ hg cat -T '{path}\n' 're:^sub'
   sub/repo/foo (glob)
 
+ inaccessible subrepos:
+
+  $ mv sub sub_
+  $ touch sub
+  $ hg cat .hgsub .hgsubstate
+  sub/repo = sub/repo
+  f42d5c7504a811dda50f5cf3e5e16c3330b87172 sub/repo
+  $ hg cat sub/repo/foo
+  abort: *: '$TESTTMP/issue1852a/sub/repo' (glob)
+  [255]
+  $ rm sub
+  $ mv sub_ sub
+
+ symlink traversal:
+
+#if symlink
+
+  $ mv sub/repo sub/repo_
+  $ ln -s repo_ sub/repo
+  $ hg cat .hgsub .hgsubstate
+  sub/repo = sub/repo
+  f42d5c7504a811dda50f5cf3e5e16c3330b87172 sub/repo
+  $ hg cat sub/repo/foo
+  abort: subrepo 'sub/repo' traverses symbolic link
+  [255]
+  $ rm sub/repo
+  $ mv sub/repo_ sub/repo
+
+#endif
+
  missing subrepos in working directory:
 
   $ mkdir -p tmp/sub/repo