fileset: matchctx.existing() must consider ignored files

When running:

  $ hg debugfileset 'binary() and ignored()'

getfileset() was correctly retrieving ignored files but
matchctx.existing() was not taking them in account. Just add them along
with unknown files.

mercurial/fileset.py

@@ -432,7 +432,7 b' class matchctx(object):'
     def existing(self):
         if self._status is not None:
             removed = set(self._status[3])
-            unknown = set(self._status[4])
+            unknown = set(self._status[4] + self._status[5])
         else:
             removed = set()
             unknown = set()

tests/test-fileset.t

@@ -82,6 +82,9 b' Test files properties'
   $ fileset 'binary()'
   $ fileset 'binary() and unknown()'
   bin
+  $ echo '^bin$' >> .hgignore
+  $ fileset 'binary() and ignored()'
+  bin
   $ hg add bin
   $ fileset 'binary()'
   bin