workingctx: use member variables to store ignored and clean

If some code tries to query ignored or clean files without first
calling the explicit status() method to query them, it will raise
an exception (indicating a software bug).

mercurial/context.py

@@ -564,7 +564,12 b' class workingctx(changectx):'
         if user:
             self._user = user
         if changes:
-            self._status = list(changes)
+            self._status = list(changes[:5])
+            self._ignored = changes[5]
+            self._clean = changes[6]
+        else:
+            self._ignored = None
+            self._clean = None
 
         self._extra = {}
         if extra:
@@ -624,7 +629,7 b' class workingctx(changectx):'
 
     @propertycache
     def _status(self):
-        return self._repo.status(unknown=True)
+        return self._repo.status(unknown=True)[:5]
 
     @propertycache
     def _user(self):
@@ -647,8 +652,10 b' class workingctx(changectx):'
         Unless this method is used to query the working copy status, the
         _status property will implicitly read the status using its default
         arguments."""
-        self._status = self._repo.status(ignored=ignored, clean=clean,
-                                         unknown=unknown)
+        stat = self._repo.status(ignored=ignored, clean=clean, unknown=unknown)
+        self._ignored = ignored and stat[5] or None
+        self._clean = clean and stat[6] or None
+        self._status = stat[:5]
         return self._status
 
     def manifest(self):
@@ -673,9 +680,13 b' class workingctx(changectx):'
     def unknown(self):
         return self._status[4]
     def ignored(self):
-        return self._status[5]
+        if self._ignored is None:
+            raise util.Abort(_("Ignored files requested without prior query\n"))
+        return self._ignored
     def clean(self):
-        return self._status[6]
+        if self._clean is None:
+            raise util.Abort(_("Clean files requested without prior query\n"))
+        return self._clean
     def branch(self):
         return self._extra['branch']
     def extra(self):