match: fix visitdir for roots of includes

I'm hoping to rewrite the matcher so excludes are handled by
composition of one matcher with another matcher where the second
matcher has only includes. For that to work, we need to make
visitdir() to return 'all' for directory 'foo' for a '-I foo' matcher.

mercurial/match.py

@@ -307,6 +307,7 b' class matcher(basematcher):'
             exclude = []
 
         self._anypats = bool(include or exclude)
+        self._anyincludepats = False
         self._always = False
         self._pathrestricted = bool(include or exclude or patterns)
         self.patternspat = None
@@ -324,6 +325,7 b' class matcher(basematcher):'
             kindpats = normalize(include, 'glob', root, cwd, auditor, warn)
             self.includepat, im = _buildmatch(ctx, kindpats, '(?:/|$)',
                                               listsubrepos, root)
+            self._anyincludepats = _anypats(kindpats)
             roots, dirs = _rootsanddirs(kindpats)
             self._includeroots.update(roots)
             self._includedirs.update(dirs)
@@ -381,8 +383,13 b' class matcher(basematcher):'
             return 'all'
         if dir in self._excluderoots:
             return False
-        if ((self._includeroots or self._includedirs) and
-            '.' not in self._includeroots and
+        if self._includeroots or self._includedirs:
+            if (not self._anyincludepats and
+                not self._excluderoots and
+                dir in self._includeroots):
+                # The condition above is essentially self.prefix() for includes
+                return 'all'
+            if ('.' not in self._includeroots and
             dir not in self._includeroots and
             dir not in self._includedirs and
             not any(parent in self._includeroots