fix a bug in dirstate.changes when cwd != repo.root

- use lstat instead of stat
- add a testcase (thanks to Johannes Hofmann)

mercurial/dirstate.py

@@ -380,7 +380,8 b' class dirstate:'
                 nonexistent = True
                 if not st:
                     try:
-                        st = os.lstat(fn)
+                        f = os.path.join(self.root, fn)
+                        st = os.lstat(f)
                     except OSError, inst:
                         if inst.errno != errno.ENOENT:
                             raise

tests/test-hgignore

@@ -40,3 +40,6 b' echo "--" ; hg status'
 
 echo "relglob:*" > .hgignore
 echo "--" ; hg status
+
+cd dir
+echo "--" ; hg status

tests/test-hgignore.out

@@ -32,3 +32,5 b' A dir/b.o'
 ? dir/c.o
 --
 A dir/b.o
+--
+A b.o