dirstate: don't walk ignored directories

With a pattern like '^directory$' in .hgignore, a "hg status directory"
would still walk "directory" and all its subdirs.

This is the first half of a fix for issue886.

mercurial/dirstate.py

@@ -369,6 +369,14 b' class dirstate(object):'
                           % (self.pathto(f), kind))
         return False
 
+    def _dirignore(self, f):
+        if self._ignore(f):
+            return True
+        for c in strutil.findall(f, '/'):
+            if self._ignore(f[:c]):
+                return True
+        return False
+
     def walk(self, files=None, match=util.always, badmatch=None):
         # filter out the stat
         for src, f, st in self.statwalk(files, match, badmatch=badmatch):
@@ -404,9 +412,11 b' class dirstate(object):'
             return match(file_)
 
         ignore = self._ignore
+        dirignore = self._dirignore
         if ignored:
             imatch = match
             ignore = util.never
+            dirignore = util.never
 
         # self._root may end with a path separator when self._root == '/'
         common_prefix_len = len(self._root)
@@ -492,8 +502,9 b' class dirstate(object):'
                         yield 'b', ff, None
                 continue
             if s_isdir(st.st_mode):
-                for f, src, st in findfiles(f):
-                    yield src, f, st
+                if not dirignore(nf):
+                    for f, src, st in findfiles(f):
+                        yield src, f, st
             else:
                 if nf in known:
                     continue

tests/test-walk

@@ -92,6 +92,13 b' hg rm fenugreek'
 debugwalk fenugreek
 touch new
 debugwalk new
+
+mkdir ignored
+touch ignored/file
+echo '^ignored$' > .hgignore
+debugwalk ignored
+debugwalk ignored/file
+
 chdir ..
 debugwalk -R t t/mammals/skunk
 mkdir t2

tests/test-walk.out

@@ -278,6 +278,11 b' m fenugreek fenugreek exact'
 hg debugwalk new
 f  new  new  exact
 
+hg debugwalk ignored
+
+hg debugwalk ignored/file
+f  ignored/file  ignored/file  exact
+
 cd ..
 
 hg debugwalk -R t t/mammals/skunk